Christianity in the 2nd century
Christianity in the 2nd century was largely the time of the Apostolic Fathers who were the students of the apostles of Jesus, though there is some overlap as John the Apostle may have survived into the 2nd century and Clement of Rome is said to have died at the end of the 1st century. While the Christian church was centered in Jerusalem in the 1st century, it became decentralized in the 2nd century. The 2nd century was also the time of several people who were later declared to be major heretics, such as Marcion, Valentinius, and Montanus.
Although the use of the term Christian is attested in the book of Acts from the middle of the first century, the earliest recorded use of the term Christianity (Greek: Χριστιανισμός) is by Ignatius of Antioch about 107 AD, who is also associated with modification of the sabbath, promotion of the bishop, and critique of the Judaizers.
Early practices 
At first, Christians continued to worship alongside Jewish believers and also gathered on "The Lord's Day" (Sunday) to worship and pray and celebrate the day Christ rose from the dead, but within twenty years of Jesus' death, Sunday was being regarded as the primary day of worship. Growing tensions soon led to a starker separation that was virtually complete by the time Christians refused to join in the Bar Khokba Jewish revolt of 132, however some groups of Christians retained more elements of Jewish practice. Only Marcion proposed rejection of all Jewish practice, but he was excommunicated in Rome c.144 and declared heretical by the growing proto-Orthodoxy. The various Christian denominations came to adopt some Jewish practices while rejecting others. Historians debate whether Roman government distinguished between Christians and Jews prior to Emperor Nerva's modification of the Fiscus Judaicus in 96. From then on, practicing Jews paid the tax, and Christians did not. Christianity also differed from other Roman religions in that it set out its beliefs in a clearly defined way, though the process of orthodoxy (right belief) was not underway until the period of the First seven Ecumenical Councils. Most early Christians did not own a copy of the works that later became the Christian Bible or other church works accepted by some but not canonized, such as the writings of the Apostolic Fathers, or other works today called New Testament apocrypha. Similar to Judaism, much of the original church liturgical services functioned as a means of learning these Scriptures, which initially centered around the Septuagint and the Targums.
A final uniformity of liturgical services may have become solidified after the church established a Biblical canon, possibly based on the Apostolic Constitutions and Clementine literature. Clement wrote about the order with which Jesus commanded the affairs of the Church be conducted. The liturgies are "to be celebrated, and not carelessly nor in disorder", but he did not specify what the actual liturgies were, though possible Clementine liturgies have been proposed. The Liturgy of St James was an early form, but each bishopric tended to develop its own.
Structure and the episcopacy 
In the post-Apostolic church, bishops emerged as overseers of urban Christian populations, and a hierarchy clergy gradually took on the form of episkopos (overseers, bishops), presbyters (elders), and then deacons (servants).
While Clement and New Testament writers use the terms overseer and elder interchangeably, an episcopal structure becomes more visible in the 2nd century. This structure was enforced by the teaching of apostolic succession, where a bishop becomes the spiritual successor of the previous bishop in a line tracing back to the apostles themselves.
Each Christian community had presbyters or "elders," as was the case with Jewish communities, who were also ordained and assisted the bishop; as Christianity spread, especially in rural areas, the presbyters exercised more responsibilities and took distinctive shape as priests. Deacons performed certain duties, such as tending to the poor and sick.
Role of the bishop 
Much of the official organizing of the ecclesiastical structure was done by the bishops of the church. This tradition of clarification can be seen as established by the Apostolic Fathers, who were bishops themselves.
The Catholic Encyclopedia argues that although evidence is scarce in the 2nd century, the primacy of the Church of Rome is asserted by Irenaeus of Lyons' document Against Heresies (AD 189). In response to 2nd century Gnostic teaching, Irenaeus created the first known document considered to be describing apostolic succession, including the immediate successors of Peter and Paul: Linus, Anacleutus, Clement, Evaristus, Alexander, and Sixtus. which the Catholic Church currently considers these the successors of Peter and the first popes, and through whom latter popes would claim authority.
Date of Easter 
Eastern and Western Mediterranean Christians had a history of differences and disagreements dating back to the 2nd century. Among the most significant early disagreements is the Quartodeciman controversy. Until the late 2nd century there was a difference in dating the celebration of the Christian Passover/Easter between Western churches and those of Asia Minor. The churches in Asia Minor celebrated it on the 14th of the Jewish month of Nisan, the day before Jewish Passover, regardless of what day of the week it fell on, as the Crucifixion had occurred on the day before Passover according to the Gospel of John. The Latins called them Quartodecimans, literally meaning 14'ers. At the time, the West celebrated Easter on the Sunday following the Jewish 14th of Nisan.
Victor, the bishop of Rome, attempted to declare the Nisan 14 practice heretical and excommunicate all who followed it. On this occasion Irenaeus and Polycrates of Ephesus wrote to Victor. Irenaeus reminded Victor of his predecessor more tolerant attitude and Polycrates emphatically defended the Asian practice. Victor's "excommunication" of the Asians was apparently rescinded, and the two sides reconciled as a result of the intervention of Irenaeus and other bishops,including Tertullian. Both Tertullian and Irenaeus were pupils of Polycarp,who was a student of the Apostle John and, according to Polycarp's own written words, was also a "hearer" of the other Apostles. Polycarp was a bishop in Smyrna.
Eusebius later claimed that synods and conferences of bishops were convened, which ruled "without a dissenting voice" in support of Easter on Sunday. A uniform method of computing the date of Easter was not formally addressed until 325 at the First Council of Nicaea. Today, the date still varies between West and East, but this is because the West later adopted the Gregorian calendar over the Julian calendar.
Heresies and the Biblical canon 
The Biblical canon is the set of books Christians regard as divinely inspired and thus constituting the Christian Bible. Though the Early Church used the Old Testament according to the canon of the Septuagint (LXX), the apostles did not otherwise leave a defined set of new scriptures; instead the New Testament developed over time.
The writings attributed to the apostles circulated amongst the earliest Christian communities. The Pauline epistles were circulating in collected forms by the end of the 1st century AD. Justin Martyr, in the early 2nd century, mentions the "memoirs of the apostles", which Christians called "gospels" and which were regarded as on par with the Old Testament. A four gospel canon (the Tetramorph) was asserted by Ireanaeus, who refers to it directly.
The oldest list of books for the New Testament canon is the Muratorian fragment dating to c.170. It shows that by 200 there existed a set of Christian writings somewhat similar to what is now the 27-book New Testament, which included the four gospels. Thus, while there was debate in the Early Church over the New Testament canon, the current books of the New Testament were accepted by almost all Christians by the middle of the 2nd century, with the exception of James, Hebrews, and 2nd Peter. However, these 3 books were also agreed upon and recognized as canon by church leadership shortly thereafter. Following Eusebius, the disputed books are referred to as the Antilegomena.
Early heresies 
One of the roles of bishops, and the purpose of many Christian writings, was to refute heresies. The earliest of these were generally Christological in nature, that is, they denied either Christ's (eternal) divinity or humanity. For example, Docetism held that Jesus' humanity was merely an illusion, thus denying the incarnation; whereas Arianism held that Jesus, while not merely mortal, was not eternally divine and was, therefore, of lesser status than God the Father (citing John 14:28). Trinitarianism held that God the Father, God the Son, and the Holy Spirit were all strictly one being with three hypostases. Many groups were dualistic, maintaining that reality was composed into two radically opposing parts: matter, usually seen as evil, and spirit, seen as good. Orthodox Christianity, on the other hand, held that both the material and spiritual worlds were created by God and were therefore both good, and that this was represented in the unified divine and human natures of Christ.
Irenaeus was the first to argue that his "proto-orthodox" position was the same faith that Jesus gave to the twelve apostles and that the identity of the apostles, their successors, and the teachings of the same were all well-known public knowledge. This was therefore an early argument supported by apostolic succession. Irenaeus first established the doctrine of four gospels and no more, with the synoptic gospels interpreted in the light of the Gospel of John. Irenaeus' opponents, however, claimed to have received secret teachings (gnosis) from Jesus via other apostles which were not publicly known, or in the case of Valentinius from Paul. Gnosticism is predicated on the existence of such hidden knowledge, but brief references to private teachings of Jesus have also survived in the canonic Scripture (Mark 4:11) as did warning by the Christ that there would be false prophets or false teachers. Irenaeus' opponents also claimed that the wellsprings of divine inspiration were not dried up, which is the doctrine of continuing revelation.
In the middle of the 2nd century, three unorthodox groups of Christians adhered to a range of doctrines that divided the Christian communities of Rome: the teacher Marcion; the pentecostal outpourings of ecstatic Christian prophets of a continuing revelation, in a movement that was called "Montanism" because it had been initiated by Montanus and his female disciples; and the gnostic teachings of Valentinus. Early attacks upon alleged heresies formed the matter of Tertullian's Prescription Against Heretics (in 44 chapters, written from Rome), and of Irenaeus' Against Heresies (ca 180, in five volumes), written in Lyons after his return from a visit to Rome. The letters of Ignatius of Antioch and Polycarp of Smyrna to various churches warned against false teachers, and the Epistle of Barnabas accepted by many Christians as part of Scripture in the 2nd century, warned about mixing Judaism with Christianity, as did other writers, leading to decisions reached in the first ecumenical council, which was convoked by Emperor Constantine at Nicaea in 325 in response to further disruptive polemical controversy within the Christian community, in that case Arian disputes over the nature of the Trinity.
The New Testament speaks of the importance of maintaining orthodox doctrine and refuting heresies, showing the antiquity of the concern. Because of the biblical proscription against false prophets (notably the Gospels of Matthew and Mark) Christianity has always been preoccupied with the "correct", or orthodox, interpretation of the faith. As there were differing opinions among the bishops, defining orthodoxy consumed the Church for some time (and still does, hence, "denominations").
In his book Orthodoxy, Christian Apologist and writer G. K. Chesterton asserts that there have been substantial disagreements about faith from the time of the New Testament and Jesus. He pointed out that the apostles all argued against changing the teachings of Christ as did the earliest church fathers. Jesus also refers to false prophets (Mark 13:21–23) and the "darnel" (Matthew 13:25–30, 13:36–43) of the flock and how their distortion of the Christian faith is to be rejected.
The development of doctrine, the position of orthodoxy, and the relationship between the various opinions is a matter of continuing academic debate. Since most Christians today subscribe to the doctrines established by the Nicene Creed, modern Christian theologians tend to regard the early debates as a unified orthodox position against a minority of heretics. Other scholars, drawing upon, among other things, distinctions between Jewish Christians, Pauline Christians, and other groups such as Gnostics and Marcionites, argue that early Christianity was fragmented, with contemporaneous competing orthodoxies.
Early writings: Apologetists and Church Fathers 
Church Fathers, Early Church Fathers, or Fathers of the Church are the early and influential theologians and writers in the Christian Church, particularly those of the first five centuries of Christian history. The term is used of writers and teachers of the Church, not necessarily "saints". In the first few centuries of its existence, the Church formed its teachings and traditions into a systematic whole under the influence of theological apologists.
As Christianity spread, it acquired certain members from well-educated circles of the Hellenistic world; they sometimes became bishops but not always. They produced two sorts of works: theological and "apologetic", the latter being works aimed at defending the faith by using reason to refute arguments against the veracity of Christianity. These authors are known as the Church Fathers, and study of them is called Patristics.
A huge quantity of theological reflection emerged in the early centuries of the Christian church – in a wide variety of genres, in a variety of contexts, and in several languages – much of it the product of attempts to discuss how Christian faith should be lived in cultures very different from the one in which it was born. So, for instance, a good deal of the Greek language literature can be read as an attempt to come to terms with Hellenistic culture. The period sees the slow emergence of orthodoxy (the idea of which seems to emerge out of the conflicts between orthodox Christianity and Gnosticism), and the establishment of a Biblical canon.
In the face of criticism from Greek philosophers and facing persecution, Apologetists wrote to justify and defend Christian doctrine.
Justin Martyr 
Justin Martyr's works represent the earliest surviving Christian "apologies" of notable size. Most of what is known about the life of Justin Martyr comes from his own writings. He was born at Flavia Neapolis (a city rebuilt in 72 from the ruins of Shechem in Iudaea Province, now modern-day Nablus). According to the traditional accounts of the church, Justin suffered martyrdom at Rome under the Emperor Marcus Aurelius when Junius Rusticus was prefect of the city (between 162 and 168).
Justin called himself a Samaritan, but his father and grandfather were probably Greek or Roman, and he was brought up a pagan. It seems that St Justin had property, studied philosophy, converted to Christianity, and devoted the rest of his life to teaching what he considered the true philosophy, still wearing his philosopher's gown to indicate that he had attained the truth. He probably traveled widely and ultimately settled in Rome as a Christian teacher.
Justin had, like others, the idea that the Greek philosophers had derived, if not borrowed, the most essential elements of truth found in their teaching from the Hebrew Bible. Thus he does not scruple to declare that Socrates and Heraclitus were Christians (Apol., i. 46, ii. 10). His aim, of course, is to emphasize the absolute significance of Christ, so that all that ever existed of virtue and truth may be referred to him. The old philosophers and law-givers had only a part of the Logos, while the whole appears in Christ.
- The First Apology of Justin Martyr is addressed to Antoninus Pius, his sons, and the Roman Senate.
- In the Dialogue with Trypho, after an introductory section, Justin undertakes to show that Christianity is the new law for all men, and to prove from Scripture that Jesus is the Christ. The concluding section (cix.-cxlii.) demonstrates that the Christians are the true people of God.
Justin's self-perception of himself was that of a scholar. Justin was confident that his teaching is that of the Church at large. He knows of a division among the orthodox only on the question of the millennium and on the attitude toward the milder Jewish Christianity, which he personally is willing to tolerate as long as its professors in their turn do not interfere with the liberty of the Gentile converts (see Apostolic Decree); his millenarianism seems to have no connection with Judaism, but he believes firmly in a millennium, and generally in the early Christian eschatology.
Apostolic Fathers 
The earliest Church Fathers (within two generations of the Twelve apostles of Christ) are usually called the Apostolic Fathers, for reportedly knowing and studied under the apostles personally. Important Apostolic Fathers of the 2nd century include Ignatius of Antioch and Polycarp of Smyrna. In addition, the Shepherd of Hermas is usually placed among the writings of the Apostolic Fathers although its authors is unknown.
Ignatius of Antioch (also known as Theophorus) was the third Bishop or Patriarch of Antioch and a student of the Apostle John. En route to his martyrdom in Rome, Ignatius wrote a series of letters which have been preserved as an example of the theology of the earliest Christians. Important topics addressed in these letters include ecclesiology, the sacraments, the role of bishops, and Biblical Sabbath. He is the second after Clement to mention Paul's epistles.
On the role of the bishop in the church, Ignatius wrote much. He spoke in "praise of unity" in a Letter to the Ephesians, saying "He, therefore, that does not assemble with the Church, has even by this manifested his pride, and condemned himself. For it is written, 'God resisteth the proud.' Let us be careful, then, not to set ourselves in opposition to the bishop, in order that we may be subject to God". Stressing the relationship between the Church initiated by Jesus and the hierarchy set in motion by the apostles, Ignatius writes: "we should look upon the bishop even as we would upon the Lord Himself" (§6). Ignatius stresses the hierarchical relationship between God and the bishop more strongly to the Magnesians urging them "to yield him all reverence, having respect to the power of God the Father, ... submitting to him, or rather not to him, but to the Father of Jesus Christ, the bishop of us all". In §6 he exhorts them to harmony, and in §13 urges them to "[s]tudy ... to be established in the doctrines of the Lord and the apostles, ... with your most admirable bishop...." Thus Ignatius emphasizes unity, obedience, and the hierarchical relationship among the faithful and between the bishop and God. Further elements of the hierarchical relationship are mentioned by St. Clement of Alexandria, referring to advice in the "holy books: some for presbyters, some for bishops and deacons" (Jurgens §413), and writing treatises with titles "On the Unity and Excellence of the Church" and "On the Offices of Bishops, Presbyters, Deacons, and Widows." In his Stromateis, Clement of Alexandria writes that "according to my opinion, the grades here in the Church, of bishops, presbyters, deacons, are imitations of the angelic glory, and of that economy which, the Scriptures say, awaits those who, following the footsteps of the apostles, have lived in perfection of righteousness according to the Gospel".
Polycarp of Smyrna was a bishop of Smyrna (now İzmir in Turkey). It is recorded that he had been a disciple of John. The options for this John are John the son of Zebedee traditionally viewed as the author of the fourth Gospel, or John the Presbyter. Traditional advocates follow Eusebius in insisting that the apostolic connection of Papius was with John the Evangelist, and that this John, the author of the Gospel of John, was the same as the Apostle John. Polycarp, c 156, tried and failed to persuade Anicetus, Bishop of Rome, to have the West celebrate Easter on 14 Nisan, as in the East. He rejected the pope's suggestion that the East use the Western date. In 155, the Smyrnans demanded Polycarp's execution, and he died a martyr. Legend states that the flames built to kill him refused to burn him, and that when he was stabbed to death; so much blood issued from his body that it quenched the flames around him. Polycarp is recognized as a saint in both the Roman Catholic and Eastern Orthodox churches.
Shepherd of Hermas 
The Shepherd of Hermas was popular in the early church, considered a valuable book by many Christians, and considered canonical scripture by some of the early Church fathers. It was written at Rome, in Greek. The Shepherd had great authority in the 2nd and 3rd centuries. It was cited as Scripture by Irenaeus and Tertullian and was bound with the New Testament in the Codex Sinaiticus, and it was listed between the Acts of the Apostles and the Acts of Paul in the stichometrical list of the Codex Claromontanus. Other early Christians, however, considered the work to be apocryphal.
Greek Fathers 
Irenaeus of Lyons was bishop of Lugdunum in Gaul, which is now Lyons, France. His writings were formative in the early development of Christian theology, and he is recognized as a saint by both the Eastern Orthodox Church and the Roman Catholic Church. He was a notable early apologetic. He was also a disciple of Polycarp, who was said to be a disciple of John the Evangelist.
His best-known book, Against Heresies (c. 180) enumerated heresies and attacked them. Irenaeus wrote that the only way for Christians to retain unity was to humbly accept one doctrinal authority—episcopal councils. Irenaeus was the first to propose that all four gospels be accepted as canonical.
Clement of Alexandria was a Christian theologian and the head of the noted Catechetical School of Alexandria. Clement is best remembered as the teacher of Origen. He used the term "gnostic" for Christians who had attained the deeper teaching of the Logos. He developed a Christian Platonism. He presented the goal of Christian life as deification, identified both as Platonism's assimilation into God and the biblical imitation of God.
Clement's parents seem to have been wealthy pagans of some social standing. The thoroughness of his education is shown by his prolific quotation of the Greek poets and philosophers. He travelled in Greece, Italy, and Egypt. He became the colleague of Pantaenus, the head of the Catechetical School of Alexandria, and finally succeeded him in the direction of the school. One of his most popular pupils was Origen. Alexandria had a major Christian community in early Christianity, noted for its scholarship and its high-quality copies of Scripture known as the Alexandrian text-type. During the persecution of Christians by Septimius Severus (202 or 203) he sought refuge with Alexander, then Cappadocia.
The trilogy into which Clement's principal remains are connected by their purpose and mode of treatment is composed of:
The first book deals with the religious basis of Christian morality, the second and third with the individual cases of conduct. As with Epictetus, true virtue shows itself with him in its external evidences by a natural, simple, and moderate way of living. Besides the great trilogy, the only complete work preserved is the treatise "Who is the Rich Man that Shall Be Saved?" based on Mark 10:17-31, and laying down the principle that not the possession of riches but their misuse is to be condemned.
The significance of Clement in the history of the development of doctrine is, according to Adolf von Harnack, that he knew how to replace the apologetic method by the constructive or systematic, to turn the simple church tradition into a "scientific" dogmatic theology. It is a marked characteristic of his that he sees only superficial and transient disagreement where others find a fundamental opposition. He is able to reconcile, or even to fuse, differing views to an extent which makes it almost impossible to attribute to him a definite individual system. He is admittedly an eclectic (Stromata, i. 37). This attitude determines especially his treatment of non-Christian philosophy.
Latin Fathers 
He wrote three books in Greek and was the first great writer of Latin Christianity, thus sometimes known as the "Father of the Latin Church". He was evidently a lawyer in Rome. He is said to have introduced the Latin term "trinitas" with regard to the Divine (Trinity) to the Christian vocabulary (but Theophilus of Antioch already wrote of "the Trinity, of God, and His Word, and His wisdom", which is similar but not identical to the Trinitarian wording), and also probably the formula "three Persons, one Substance" as the Latin "tres Personae, una Substantia" (itself from the Koine Greek "treis Hypostases, Homoousios"), and also the terms "vetus testamentum" (Old Testament) and "novum testamentum" (New Testament).
In his Apologeticus, he was the first Latin author who qualified Christianity as the "vera religio" and systematically relegated the classical Roman Empire religion and other accepted cults to the position of mere "superstitions". Later in life, Tertullian is thought by most to have joined the Montanists, a heretical sect that appealed to his rigorism.
Spread of Christianity 
Jerusalem had the prestige of being the city of Christ's death and resurrection, and was the center of the Apostolic Age, but it experienced decline during the years of the Jewish–Roman wars (66-135). Traditionally it is believed the Jerusalem Christians waited out the Jewish–Roman wars in Pella in the Decapolis. Jerusalem's bishops became suffragans (subordinates) of the Metropolitan bishop in nearby Caesarea, and the Holy Land did not regain significance to greater Christianity until the pilgrimage of the Empress Helena c.326.
Rome, the capital of the Roman Empire until 330, was the most important Christian center in the Western Roman Empire. Antioch, Alexandria, and others were important centers of Christian thought in the Eastern Roman Empire. Christianity also spread outside of the Roman Empire.
Illegal churches (before "Christian legalization") are mentioned throughout church history. Of the underground churches that existed before legalization, some are recorded to have existed as the catacombs in Europe, Catacombs of Rome, Greece (see Cave of the Apocalypse, The Church of St George and the church at Pergamon) and also in the underground cities of Anatolia such as Derinkuyu Underground City (also see Cave monastery and Bab Kisan).
Church of Antioch 
Origin and expansion of the Church of the East 
The church which spread throughout most of Asia bears the appellation "Nestorian," after the 5th century patriarch of Constantinople, Nestorius, who was condemned by Rome as a heretic in AD 430. The name is actually a misnomer which became current in the West; the Roman See had sought to discredit this church, which had renounced Rome's primacy for geographical, political, linguistic, and doctrinal reasons. Nestorian was not the name by which the church knew itself, nor was it so commonly designated in Asian lands. It was rather known as the Church of the East, or Easterns, to distinguish it from the Greek and Latin churches in the West which were divided by subtle theological controversies little appreciated by the Eastern Christians. It also came to be known as the Assyrian church because of the location of its successive headquarters, and also as the Luminous Religion, especially in China.
This ancient church claimed a 1st-century origin and developed almost wholly apart from the Greek and Roman churches, using the Aramaic language. It did not embrace the heresy of which Nestorius was accused, though it endorsed his opposition to the Roman doctrines of purgatory and Mariolatry, especially her title as "Mother of God" and or Theotokos. For at least twelve hundred years the church of the Easterns was noted for its missionary zeal, its high degree of lay participation, its superior educational standards and cultural contributions in less developed countries, and its fortitude in the face of persecution.
Parthian and Persian Empires 
The Church of the East had its inception at a very early date in the buffer zone between the Parthian and Roman Empires in Upper Mesopotamia, known as the Assyrian Church of the East. The vicissitudes of its later growth were rooted in its minority status in a situation of international tension. The rulers of the Parthian Empire were on the whole tolerant in spirit, and with the older faiths of Babylonia and Assyria in a state of decay, the time was ripe for a new and vital faith. The rulers of the Sassanid Empire also followed a policy of religious toleration to begin with, though later they gave Christians the same status as a subject race. However, these rulers also encouraged the revival of the ancient Persian dualistic faith of Zoroastrianism and established it as the state religion, with the result that the Christians were increasingly subjected to repressive measures. Nevertheless, it was not until Christianity became the state religion in the West (380) that enmity toward Rome was focused on the Eastern Christians. After the Mohammedan conquest in the 7th century, the caliphate tolerated other faiths but forbade proselytism and subjected Christians to heavy taxation.
Edessa (now Şanlıurfa) in northwestern Mesopotamia was from apostolic times the principal center of Syriac-speaking Christianity. Strategically located on the main trade routes of the Fertile Crescent, it was easily accessible from Antioch, where the mission to the Gentiles was inaugurated. When early Christians were scattered abroad because of persecution, some found refuge at Edessa. Thus the Edessan church traced its origin to the apostolic age, and Christianity even became the state religion for a time.
Thus it was from Edessa that a missionary movement began which gradually spread throughout Mesopotamia, Persia, Central Asia and China. According to tradition, Mari was sent as a missionary to Seleucia (on the Tigris River near Baghdad), which, with its twin city of Ctesiphon across the river, became another canter of missionary outreach. Mari was also regarded as the pioneer evangelist in the whole region of Adiabene to the north, of which Arbil (now Erbil) was the capital. By the latter half of the 2nd century, Christianity had spread east throughout Media, Persia, Parthia, and Bactria. The twenty bishops and many presbyters were more of the order of itinerant missionaries, passing from place to place as Paul did and supplying their needs with such occupations as merchant or craftsman. By 280 the metropolis of Seleucia assumed the title of "Catholicos,"and in 424 a council of the church at Seleucia elected the first patriarch to have jurisdiction over the whole church of the East, including India and Ceylon. The seat of the Patriarchate was fixed at Seleucia-Ctesiphon, since this was an important point on the East-West trade routes which extended both to India and China, Java and Japan. Thus the shift of ecclesiastical authority was away from Edessa, which in 216 had become tributary to Rome. The establishment of an independent patriarchate with nine subordinate metropoli contributed to a more favourable attitude by the Persian government, which no longer had to fear an ecclesiastical alliance with the common enemy, Rome.
Arabian Peninsula 
Christianity apparently gained its strongest foothold in the ancient center of Semitic civilisation in southwest Arabia or Yemen, (sometimes known as Seba or Sheba), whose queen visited Solomon. Because of geographic proximity, acculturation with Ethiopia was always strong, and the royal family traces its ancestry to this queen.
The presence of Arabians at Pentecost and Paul's three-year sojourn in Arabia suggest a very early gospel witness. A 4th-century church history states that the apostle Bartholomew preached in Arabia and that Himyarites were among his converts. Arabia's close relations with Ethiopia give significance to the conversion of the treasurer to the queen of Ethiopia, not to mention the tradition that the Apostle Matthew was assigned to this land. Eusebius says that "one Pantaneous (c.190) was sent from Alexandria as a missionary to the nations of the East,,"including southwest Arabia, on his way to India.
See also 
- List of events in early Christianity
- History of Christianity
- History of the Roman Catholic Church
- History of the Eastern Orthodox Church
- History of Christian theology
- Christian martyrs
- History of Oriental Orthodoxy
- History of early Christianity
- Ante-Nicene Period
- Church Fathers
- Great Church
- List of Church Fathers
- Persecution of Christians in the New Testament
- Hellenistic Judaism
- List of events in early Christianity
- Development of the New Testament canon
- History of Calvinist-Arminian debate
- Timeline of Christianity#Early Christianity
- Timeline of Christian missions#Early Christianity
- Timeline of the Roman Catholic Church#Up to 312 AD
- Chronological list of saints in the 2nd century
- Langan, The Catholic Tradition (1998), pp.55, 115
- Walter Bauer, Greek-English Lexicon
- Ignatius of Antioch Letter to the Magnesians 10, Letter to the Romans (Roberts-Donaldson tr., Lightfoot tr., Greek text)
- Davidson, p.115
- Davidson, p.146
- Davidson, p.149
- Wylen, pp.190-192
- Dunn, pp.33-34
- Boatwright, p.426.;
- Herring, An Introduction to the History of Christianity (2006), p. 28
- "New Advent - The Didache".
- "Early Christian Writings: The Didache (§15)".
- Catholic Encyclopedia: The Pope
- Langan, The Catholic Tradition (1998), p.107
- Eamon Duffy, Saints and Sinners, ch.1
- "Catholic Encyclopedia - List of Popes". New Advent. Retrieved 2006-12-12.
- Eusebius. "Church History". p. 5.24.
- Ferguson, pp.302–303; cf. Justin Martyr, First Apology 67.3
- Ferguson, p.301; cf. Irenaeus, Adversus Haereses 3.11.8
- H. J. De Jonge, "The New Testament Canon", in The Biblical Canons. eds. de Jonge & J. M. Auwers (Leuven University Press, 2003) p. 315
- The Cambridge History of the Bible (volume 1) eds. P. R. Ackroyd and C. F. Evans (Cambridge University Press, 1970) p. 308
- R. Gerberding and J. H. Moran Cruz, Medieval Worlds (New York: Houghton Mifflin Company, 2004) p. 58
- e.g., 11:13–15; 2:1–17; 7–11; 4–13, and the Epistle of James in general.
- Bauer, Walter (1971). Orthodoxy and Heresy in Earliest Christianity. ISBN 0-8006-1363-5.
- Pagels, Elaine (1979). The Gnostic Gospels. ISBN 0-679-72453-2.
- Norman, The Roman Catholic Church an Illustrated History (2007), pp. 27–28
- Church History, iv. 18.
- For a review of the most recent editions of the Apostolic Fathers and an overview of the current state of scholarship, see Timothy B. Sailors, "Bryn Mawr Classical Review: Review of The Apostolic Fathers: Greek Texts and English Translations". Retrieved 2013-01-25.
- EPISTLE OF IGNATIUS TO THE MAGNESIANS, chapter IX
- Durant, Will. Caesar and Christ. New York: Simon and Schuster. 1972
- "Early Christian Writings: The Epistle of Ignatius to the Ephesians (§5)".
- St. Ignatius of Antioch. "Letter to the Magnesians §3". Retrieved 2009-01-24.
- Clement of Alexandria. "Stromateis". Retrieved 2009-01-24.
- Lake 1912
- McDonald & Sanders, The Canon Debate, Appendix D-1
- "The Pastor of Hermas was one of the most popular books, if not the most popular book, in the Christian Church during the second, third and fourth centuries. It occupied a position analogous in some respects to Bunyan's Pilgrim's Progress in modern times." (F. Crombie, translator of Schaff, op. cit.).
- "Clement of Alexandria." Cross, F. L., ed. The Oxford dictionary of the Christian church. New York: Oxford University Press. 2005
- Cross, F. L., ed. The Oxford Dictionary of the Christian Church. New York: Oxford University Press. 2005, article Tertullian
-  Vincent of Lerins in 434AD, Commonitorium, 17, describes Tertullian as 'first of us among the Latins' (Quasten IV, p.549)
- Catholic Encyclopedia: Tertullian
- A History of Christian Thought, Paul Tillich, Touchstone Books, 1972. ISBN 0-671-21426-8 (p. 43)
- To Autolycus, Book 2, chapter XV
- Catholic Encyclopedia: Jerusalem (AD 71-1099)
- Catholic Encyclopedia: Jerusalem (AD. 71-1099)
- Neill, p. 28
- Jewish Encyclopedia: Tarfon
- Barrett, p. 23
- Neill, p. 30
- Ingram, James. The Saxon chronicle with an English translation and notes, critical and explanatory, 1823, p. 10
- Neill, p. 24
- Glover, 20
- Herbermann, p. 385
- Boatwright, Mary Taliaferro & Gargola, Daniel J & Talbert, Richard John Alexander, The Romans: From Village to Empire, Oxford University Press (2004), ISBN 0-19-511875-8
- Davidson, The Birth of the Church (2005)
- Dunn, James D.G., Jews and Christians: The Parting of the Ways, A.D. 70 to 135, Wm. B. Eerdmans Publishing (1999), ISBN 0-8028-4498-7
- Ferguson, Everett, "Factors leading to the Selection and Closure of the New Testament Canon", in The Canon Debate. eds. L. M. McDonald & J. A. Sanders (Hendrickson, 2002)
- Wylen, Stephen M., The Jews in the Time of Jesus: An Introduction, Paulist Press (1995), ISBN 0-8091-3610-4
Further reading 
- Berard, Wayne Daniel. When Christians Were Jews (That Is, Now). Cowley Publications (2006). ISBN 1-56101-280-7.
- Bockmuehl, Markus N.A. The Cambridge Companion to Jesus. Cambridge University Press (2001). ISBN 0-521-79678-4.
- Brown, Schuyler. The Origins of Christianity: A Historical Introduction to the New Testament. Oxford University Press (1993). ISBN 0-19-826207-8.
- Dunn, James D.G. Jews and Christians: The Parting of the Ways, AD. 70 to 135. Wm. B. Eerdmans Publishing (1999). ISBN 0-8028-4498-7.
- Dunn, James D.G. The Cambridge Companion to St. Paul. Cambridge University Press (2003). ISBN 0-521-78694-0.
- Elwell, Walter A. & Comfort, Philip Wesley. Tyndale Bible Dictionary. Tyndale House Publishers (2001). ISBN 0-8423-7089-7.
- Esler, Phillip F. The Early Christian World. Routledge (2004). ISBN 0-415-33312-1.
- Tabor, James D. "Ancient Judaism: Nazarenes and Ebionites", The Jewish Roman World of Jesus. Department of Religious Studies at the University of North Carolina at Charlotte (1998).
- White, L. Michael. From Jesus to Christianity. HarperCollins (2004). ISBN 0-06-052655-6.
- Wright, N.T. The New Testament and the People of God. Fortress Press (1992). ISBN 0-8006-2681-8.
- Wylen, Stephen M. The Jews in the Time of Jesus: An Introduction. Paulist Press (1995). ISBN 0-8091-3610-4.
- Dunn, James D.G. Unity and Diversity in the New Testament: An Inquiry into the Character of Earliest Christianity. SCM Press (2006). ISBN 0-334-02998-8.
- Freedman, David Noel (Ed). Eerdmans Dictionary of the Bible. Wm. B. Eerdmans Publishing (2000). ISBN 0-8028-2400-5.
- Keck, Leander E. Paul and His Letters. Fortress Press (1988). ISBN 0-8006-2340-1.
- Mills, Watson E. Acts and Pauline Writings. Mercer University Press (1997). ISBN 0-86554-512-X.
- Pelikan, Jaroslav Jan. The Christian Tradition: The Emergence of the Catholic Tradition (100-600). University of Chicago Press (1975). ISBN 0-226-65371-4.
- Internet Ancient History Sourcebook: Christian Origins
- Guide to Early Church Documents
- Chart of Church Fathers at ReligionFacts.com
- Church Fathers' works in English edited by Philip Schaff, at the Christian Classics Ethereal Library
- Church Fathers at Newadvent.org
- Faulkner University Patristics Project A growing collection of English translations of patristic texts and high-resolution scans from the comprehensive Patrologia compiled by J. P. Migne.
- Primer on the Church Fathers at Corunum
- New Schaff-Herzog Encyclopedia of Religious Knowledge
- Catholic Encyclopedia: St. Justin Martyr
|History of Christianity: Early Christianity|
the 1st century
the 3rd century