Patristics or patrology is the study of the early Christian writers who are designated Church Fathers. The names derive from the combined forms of Latin pater and Greek patḗr (father). The period is generally considered to run from the end of New Testament times or end of the Apostolic Age (c. AD 100) to either AD 451 (the date of the Council of Chalcedon) or to the 8th century Second Council of Nicaea.
Among those whose writings form the basis for Patristics, (i.e. prominent early Church Fathers), are:
- Ignatius of Antioch (c. 35-c.108),
- Pope Clement I (c.1st century AD-c.101),
- Justin Martyr (c.100-c.165),
- Irenaeus of Lyons (c.120-c.202),
- Clement of Alexandria (c.150-c.215),
- Tertullian (c.160-c.225),
- Origen (c.185-c.254),
- Cyprian of Carthage (d. 258),
- Athanasius (c.296-c.373),
- Gregory of Nazianzus (329-389),
- Basil of Caesarea (c.330-379),
- Gregory of Nyssa (c.330-c.395)
- Theodore of Mopsuestia (c.350-428),
- Jerome (347-430),
- Augustine of Hippo (354-430),
- Vincent of Lérins (d. bef. 450),
- Cyril of Alexandria (d.444),
- Maximus the Confessor (580-662)
- Isaac of Nineveh (d. 700)
Key theological developments
Major focuses for these theologians during the period are in chronological order: Christianity's relationship with Judaism; the establishment of the New Testament Canon; Apologetics ('defense' or 'explanation' of Christianity); and doctrinal discussions that sought to achieve consistency of faith, in particular within the Christianised Roman Empire. Following the scholar of Christianity Alister McGrath (1998), several major areas of theology can be seen to have developed during the Patristic Period: the extent of the New Testament Canon, the role of tradition, the fixing of the ecumenical creeds, the Two Natures of Christ, the doctrine of the Trinity, the doctrine of the Church, and the doctrine of Divine grace.
Eras of the church fathers
The church fathers are generally divided into the Ante-Nicene Fathers, those who lived and wrote before the Council of Nicaea (325) and the Nicene and Post-Nicene Fathers, those who lived and wrote after 325. In addition, the division of the fathers into Greek and Latin writers is also common. Some of the most prominent Greek Fathers are Justin Martyr, John Chrysostom, and Cyril of Alexandria. Among the Latin Fathers are Tertullian, Cyprian, Jerome, Ambrose of Milan, Gregory the Great and Augustine of Hippo.
There were also church fathers who wrote in languages other than Greek or Latin, such as Coptic, Syriac, Ge'ez, and Armenian, among others.  Historically, Chalcedonian Christians have had less interest in these authors since the associated churches ended up rejecting the councils of Chalcedon (becoming Oriental Orthodox), or Ephesus (becoming the Church of the East). Recently this has begun to change, with the cooling of tensions between these branches of Christianity and the Western and Byzantine ones. There are Eastern Catholics who follow Oriental rites while remaining in communion with Rome, and at least one organization argues that Eastern and Oriental Orthodox Christians now share the same faith.
Obstacles to 21st century understanding
- Some of the debates appear to have little relevance to the modern world
- the use of classical philosophy
- the doctrinal diversity
- the divisions between East and West, i.e., Greek and Latin methods of theology, the extent of use of classical philosophy.
The terms neo-patristics and post-patristics refer to recent theologies according to which the Church Fathers must be reinterpreted or even critically tested in light of modern developments since their writings reflected that of a distant past. These theologies, however, are considered controversial or even dangerous by orthodox theologians.
Patrologia vs. patristica
Some scholars, chiefly in Germany, distinguish patrologia from patristica. Josef Fessler, for instance, defines patrologia as the science which provides all that is necessary for the using of the works of the Fathers, dealing, therefore, with their authority, the criteria for judging their genuineness, the difficulties to be met within them, and the rules for their use. But Fessler's own Institutiones Patrologiae has a larger range, as have similar works entitled Patrologies, for example that of Otto Bardenhewer (tr. Shahan, Freiburg, 1908).
On the other hand, Fessler describes patristica as that theological science by which all that concerns faith, morals, or discipline in the writings of the Fathers is collected and sorted. The lives and works of the Fathers are also described by a non-specialized science: literary history. These distinctions are not much observed, nor do they seem very necessary; they are nothing else than aspects of patristic study as it forms part of fundamental theology, of positive theology, and of literary history.
Availability of patristic texts
Most patristic texts are available in their original languages in Jacques Paul Migne's two great patrologies, Patrologia Latina and Patrologia Graeca. For Syriac and other Eastern languages the Patrologia Orientalis is less complete and can be largely supplemented by the Corpus Scriptorum Christianorum Orientalium. Noted collections containing re-edited patristic texts (also discoveries and new attributions) are the Corpus Christianorum, Sources Chrétiennes, Corpus Scriptorum Ecclesiasticorum Latinorum, and on a lesser scale Oxford Early Christian Texts and Fontes Christiani (also Etudes Augustiniennes). [clarification needed]
English translations of patristic texts are readily available in a variety of collections. For example:
- A Select Library of the Nicene and Post-Nicene Fathers of the Christian Church (Edinburgh: T&T Clark).
- The Works of Saint Augustine: A Translation for the Twenty-First Century (New York: New City Press). 
- The Fathers of the Church (Washington, D.C.: Catholic University of America Press) 
- Ancient Christian Writers (New York: Paulist Press) 
- The Early Church Fathers (London; New York: Routledge). 
- The Popular Patristics Series (Crestwood, NY: St. Vladimir's Seminary Press) 
A range of journals cover patristic studies:
- Augustinian Studies
- Church History (journal)
- The Journal of Ecclesiastical History
- Journal of Early Christian Studies
- Studia patristica
- Vigiliae Christianae
- Armenian studies
- Early Christianity
- Ethiopian Studies
- First seven Ecumenical Councils
- Historiography of early Christianity
- Nag Hammadi library
- Syriac studies
- McGrath, Alister. 1998. Historical Theology: An Introduction to the History of Christian Thought. Oxford: Blackwell Publishers. Chapter 1 'The Patristic Period, c. 100-451.'
- McGrath. op.cit. Ch. 1.
- McGrath. op.cit. pp. 27-37.
- Alopen, a key patristic-era figure in the Church Of The East, wrote in Chinese.
- McGrath. op.cit. pp. 20-22.
- McGrath. op.cit. pp. 23.
- Dr. Triantafyllos Sioulis, «Πατερικός φονταμενταλισμός» ή «μετα-πατερική θεολογική θολούρα»
- Metropolitan of Nafpaktus ΝΕΟΠΑΤΕΡΙΚΗ ΚΑΙ ΜΕΤΑΠΑΤΕΡΙΚΗ "ΘΕΟΛΟΓΙΑ"
- Alin Suciu's blog on Patristic literature
- Catholic Encyclopedia- Patrology
- Free digital bilingual edition (french - greek or latin) of patristic texts, studies, meditations, prayers.
- Ante-Nicene, Nicene and Post Nicene Fathers Collection A 38 volume set containing most of the major works of the first 800 years of Christian patristic writings.
- Early Church Texts A site with a growing number of original language patristic texts and translations, together with an extensive set of links to online resources about the Early Church.
- Corunum Large collection of patristic texts that outline the cardinal doctrines of the Catholic faith.
- Ecole Initiative Online collection of patristic texts, images, and information.
- 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.
- Patristics In English Project An online initiative whose aim is to scan and present all out of copyright patristic texts as well as providing new translations of previously untranslated patristic texts.
- St. Pachomius Library Large collection of various patristic texts and information dealing with Eastern Orthodoxy.
- The Tertullian Project A scholarly site devoted to the study of the 2nd-century Latin patristic writer Tertullian. Also includes many out of copyright patristic texts.
- International Association of Patristics Studies
- L'Istituto Patristico Augustinianum di Roma
- North American Patristics Society
- "Way of the Fathers" Weblog
- Roger Pearse weblog - mainly patristic
- Migne Patrologia Latina and Graeca free digital edition of almost all the texts.
- Fourth Century Christianity -College website devoted to 4th-century Christianity
- Gérard Vallée, The shaping of Christianity