Over time, schisms have disrupted the unity of Christianity. The major divisions occurred in c.144 with Marcionism, 318 with Arianism, in 1054 the East–West Schism of the Catholic Church with the Eastern Orthodox churches and in 1517 with the Protestant Reformation. The Catholic Church has been the moving force in some of the major events of world history including the evangelization of Europe and Latin America, the spreading of literacy and the foundation of the universities, hospitals, Western monasticism, the development of art, music, literature, architecture, the scientific method, and trial by jury. Also playing a role in world affairs including, the Inquisition, the Crusades, an analytical philosophical method, and the downfall of communism in Eastern Europe in the late 20th century.
Although the calculations of Dionysius Exiguus put the birth of Jesus in the year that in consequence is called AD 1, history places his birth more likely some time between 6 and 4 BC.
c. 28: Jesus' baptism, start of ministry, and selection of the Apostles. The Gospel of Luke indicates that Christ was baptized during the 15th reign of Tiberius Caesar which is dated in 28 AD (found in Luke 3:1,21,22). Christian Gospels strongly suggest Peter as leader and spokesman of the Apostles of Jesus, being mentioned the most number of times in the Gospels. Peter, and the sons of Zebedee, James and John, constitute the inner circle of the Apostles of Jesus, being witnesses to specific important events of the life of Jesus; preachings of Jesus, such as the Sermon on the Mount; and performance of miracles, such as raising the dead back to life, feeding five-thousand, walking on water, etc.
c. 31: Peter declares and other followers believe Jesus of Nazareth to be the Jewish Messiah promised by Yahweh according to the Jewish Scriptures and the predictions of the Hebrew prophets. Entry into Jerusalem, start of Passion of Christ. Jesus of Nazareth is crucified in Jerusalem under Pontius Pilate, procurator of Judea during the reign of Tiberius and Herod Antipas, after the Sanhedrin, under the High Priest Caiaphas, accuse Jesus of blasphemy. He was then crucified under Pontius Pilate. According to his followers, three days later, "God raised him from the dead". Forty days after his resurrection (Ascension), the Christian Gospels narrate that Jesus instructed His disciples thus: "All authority has been given to me in heaven and on earth. Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of time." (Matthew 28:18–20). Ten days later (Pentecost) Peter makes the first sermon converting 3,000 to be baptized.
c. 110: Ignatius of Antioch uses the term Catholic Church in a letter to the Church at Smyrna, one of the letters of undisputed authenticity attributed to him. In this and other genuine letters he insists on the importance of the bishops in the Church and speaks harshly about heretics and Judaizers.
c. 150: Latin translations (the Vetus Latina) from the Greek texts of the Scriptures are circulated among non-Greek-speaking Christian communities.
January 20, 250: Emperor Decius begins a widespread persecution of Christians in Rome. Pope Fabian is martyred. Afterwards the Donatist controversy over readmitting lapsed Christians disaffects many in North Africa.
October 28, 312: Emperor Constantine leads the forces of the Roman Empire to victory at the Battle of the Milvian Bridge. Tradition has it that, the night before the battle, Constantine had a vision that he would achieve victory if he fought under the Symbol of Christ; accordingly, his soldiers bore on their shields the Chi-Rho sign composed of the first two letters of the Greek word for "Christ" (ΧΡΙΣΤΌΣ).
321: Granting the Church the right to hold property, Constantine donates the palace of the Laterani to Pope Miltiades. The Lateran Basilica (Basilica of Our Savior) becomes the episcopal seat of the Bishop of Rome.
November 3, 324: Constantine lays the foundations of the new capital of the Roman Empire in Byzantium, later to be known as Constantinople.
325: The Arian controversy erupts in Alexandria, causing widespread violence and disruptions among Christians.
391: The Theodosian decrees outlaw most pagan rituals still practiced in Rome, thereby encouraging much of the population to convert to Christianity.
400: Jerome's Vulgate Latin Bible translation is published. This remained the standard text in the Catholic world until the Renaissance, was used in Catholic services until the late 20th century, and remains an influence on modern vernacular translations.
August 24, 410: Sack of Rome. Alaric and his Visigoths burst in by the Porta Salaria on the northeast of the city Rome.
431: The Ecumenical Council of Ephesus declares that Jesus existed both as Man and God simultaneously, clarifying his status in the Holy Trinity. The meaning of the Nicene Creed is also declared a permanent holy text of the church.
November 1, 451: The Council of Chalcedon, the fourth ecumenical council, closes. The Chalcedonian Creed is issued, which re-asserts Jesus as True God and True Man and the dogma of the Virgin Mary as the Mother of God. The council excommunicatesEutyches, leading to the schism with Oriental Orthodoxy.
September 4, 476: Emperor Romulus Augustus is deposed in Rome, marked by many as the fall of the Western Roman Empire. The focus of the early Church switches to expanding in the Eastern Roman Empire, also known as the Byzantine Empire, with its capital at Constantinople.
Justinian I depicted on a mosaic in the church of San Vitale, Ravenna, Italy
480: Traditional birth of St Benedict, author of a Monastic Rule, setting out regulations for the establishment of monasteries.
496: Clovis I pagan King of the Franks, converts to the Catholic faith.
502: Pope Symmachus ruled that laymen should no longer vote for the popes and that only higher clergy should be considered eligible.
529: The Codex Justinianus (Code of Justinian) completed. First part of Corpus Iuris Civilis (Body of Civil Law).
January 2, 533: Mercurius becomes Pope John II. He becomes the first pope to take a regnal name. John II obtains valuable gifts as well as a profession of orthodox faith from the Byzantine emperor Justinian.
533: The Digest, or Pandects, was issued; second part of Corpus Iuris Civilis (Body of Civil Law). The Institutes, third part of Corpus Iuris Civilis (Body of Civil Law) comes into force of law.
685: The Maradites used their power and importance to choose John Maron, one of their own, as Patriarch of Antioch and all the East. John received the approval of Pope Sergius I, and became the first Maronite Patriarch.
1098: Foundation of the reforming monastery of Cîteaux, leads to the growth of the Cistercian order.
1099: Retaking of Jerusalem by the 1st Crusade, followed by a massacre of the remaining non-Christian inhabitants, and the establishment of the Crusader kingdoms, in Latin bishops are appointed to dioceses still largely populated by the Orthodox.
Notre-Dame Cathedral – designed in the Gothic architectural style.
1241: The death of Ögedei Khan, the Great Khan of the Mongols, prevented the Mongols from further advancing into Europe after their easy victories over the combined Christian armies in the Battle of Liegnitz (in present-day Poland) and Battle of Mohi (in present-day Hungary).
November 18, 1302: Pope Boniface VIII issues the Papal bull Unam sanctam.
1305: French influence causes the Pope to move from Rome to Avignon.
August 12, 1308: Pope Clement V issues the Bull Regnans in coelis calling a general council to meet on October 1, 1310, at Vienne in France for the purpose "of making provision in regard to the Order of Knights Templar, both the individual members and its lands, and in regard to other things in reference to the Catholic Faith, the Holy Land, and the improvement of the Church and of ecclesiastical persons".
1387: Lithuanians were the last in Europe to accept the Catholic faith.
c. 1412–1431: St. Joan of Arc, a peasant girl from France, has visions from God telling her to lead her countrymen to reclaim their land from the English. After success in battle she is captured by the English in 1431 and is condemned as a heretic and was executed by burning at the age of 19. Later investigation authorized by Pope Callixtus III would conclude she was innocent and a martyr.
1440: Johannes Gutenberg completes his wooden printing press using moveable metal type revolutionizing the spread of knowledge by cheaper and faster means of reproduction. Soon results in the large scale production of religious books including Bibles.
1543: A full account of the heliocentric Copernican theory titled, On the Revolutions of the Heavenly Spheres (De Revolutionibus Orbium Coelestium) is published. Considered as the start of the Scientific Revolution.
December 13, 1545: Ecumenical Council of Trent convened during the pontificate of Paul III, to prepare the Catholic response to the Protestant Reformation. Its rulings set the tone of Catholic society for at least three centuries.
December 4, 1563: Ecumenical Council of Trent closed. The decrees were confirmed on January 26, 1564, by Pius IV in the Bull "Benedictus Deus".
1600: Pope Clement VIII sanctions use of coffee despite petition by priests to ban the Muslim drink as "the devil's drink". The Pope tried a cup and declared it "so delicious that it would be a pity to let the infidels have exclusive use of it. We shall cheat Satan by baptizing it."
April 28, 1738: Pope Clement XII publishes the Bull In Eminenti forbidding Catholics from joining, aiding, socializing or otherwise directly or indirectly helping the organizations of Freemasonry and Freemasons under pain of excommunication. Membership to any secret society would also incur the penalty of excommunication.
July 16, 1802: French Concordat of 1801. The Catholic Church re-established in France.
December 2, 1804: Napoleon crowns himself Emperor of the French in the Cathedral of Notre Dame, Paris, in the presence of Pope Pius VII.
1846: Pope Pius IX begins his reign. During his reign he asks that an antiCatholic document written by Freemasons known as the Alta Vendita be distributed to alert Catholic officials of possible Masonic infiltration.
July 18, 1870 – The Dogmatic Constitution of the Church of Christ from the fourth session of Vatican I, "Pastor Aeternus", issues the dogma of papal infallibility among other issues before the fall of Rome in the Franco-Prussian War causes it to end prematurely and brings an end to the Papal States. Controversy over several issues leads to the formation of the Old Catholic Church. This council was not formally closed until 1960 by Pope John XXIII in preparation for the Second Vatican Council.
1903–1914:SaintPope Pius X numerous reforms, staunch defender of the faith, introducing frequent communion, promoting Gregorian chant. Problems with France. He is the most recent Pope to be canonized a saint. Prior to him was Pope St. Pius V.
1914–1918 Pope Benedict XV declares neutrality during World War I. His peace initiatives are rejected by both sides as favoring the other. Massive papal charity in Europe.
1916: Charles I of Austria is crowned Emperor of the Austro-Hungarian Empire. He is one of the last Catholic monarchs. Charles attempted to negotiate peace between the warring nations during World War I. His attempts at peace are largely ignored.
September 1, 1939: Germany invades Poland. Start of the Second World War. The Vatican, after trying to avoid the war, declares neutrality to avoid being drawn into the conflict. Massive Vatican relief intervention for displaced persons, prisoners of war and needy civilians in Europe. In 1939 St Patrick's Cathedral, Melbourne, Victoria, Australia was finished being built.
During World War II: Convents, monasteries, and the Vatican are used to hide Jews and others targeted by the Nazis for extermination. (see The Myth of Hitler's Pope) St. Maximilian Kolbe is martyred in Auschwitz concentration camp after volunteering to die in place of a stranger. The Nazis imprison and at times execute Catholic clergy, monks and nuns not compliant to Nazi ideology.
1944: The German Army occupies Rome. Adolf Hitler proclaims he will respect Vatican neutrality; however several incidents, such as giving aid to downed Allied airmen, nearly cause Nazi Germany to invade the Vatican. Rome is liberated by the Allies after only a few weeks of occupation.
1960: Senator John F. Kennedy is elected president, making him the only Roman Catholic president in United States history
October 11, 1962: Pope John XXIII opens the Second Ecumenical Vatican Council. The 21st ecumenical council of the Catholic Church emphasized the universal call to holiness and brought many changes in practices, including an increased emphasis on ecumenism; fewer rules on penances, fasting and other devotional practices; and initiating a revision of the services, which were to be slightly simplified and made supposedly more accessible by allowing the use of native languages instead of Latin. Opposition to changes inspired by the Council gave rise to the movement of Traditionalist Catholics who disagree with changing the old forms of worship and disagree with the rise of previously condemned philosophies now being adopted by clergy and laity.
December 7, 1965: Joint Catholic-Orthodox Declaration of Pope Paul VI and the Ecumenical Patriarch Athenagoras I. Mutual excommunication of the Great Schism of 1054 against Catholic and Orthodox is lifted by both parties.
December 8, 1965: Pope Paul VI solemnly closes the Second Vatican Council.
June 30, 1988: Archbishop Marcel Lefebvre of the Society of St. Pius X (SSPX), consecrates four men as bishops at Écône, Switzerland without the express permission of the Pope. Lefebvre et al. automatically incurs excommunication according to canon law. Traditionalist bishops of the SSPX continue to be suspended "a divinis" to this day.
December 31, 1991: The Soviet Union is officially dissolved. Persecuted Catholic Church re-emerges from hiding, especially in the Ukraine and Baltic states.
April 30, 2000 : Pope John Paul II canonized St. Faustina and designated the Sunday after Easter as Divine Mercy Sunday in the General Roman Calendar, with effect from the following year.
January 1, 2001: The 21st century and the new millennium begin. The Church solemnizes the start of the third Christian millennium by extending into part of the year 2001 the jubilee year that it observes at 25-year intervals and that, in the case of the year 2000, it called the Great Jubilee.
January 6, 2001: John Paul II issues Novo Millennio Ineunte, a program for the Church in the new millennium, wherein he placed sanctity through a training in prayer as the most important priority of the Catholic Church in consonance with its purpose.
April 2, 2005: Pope John Paul II dies at the age of 84. His funeral is broadcast to every corner of the globe through the modern media. Millions of Catholic pilgrims journey to Rome to pay final respects.
August 18, 2005: Pope Benedict XVI attends the World Youth Day in Cologne, Germany, his first trip outside Italy.
September 12, 2006: Pope Benedict XVI delivers address on Faith, Reason in University of Regensburg. Benedict maintained that in the Western world, to a large degree, only positivistic reason and philosophy are valid. A concept of reason which excludes the divine, is incapable of entering into the dialogue of cultures, according to Benedict. He quoted negative views of Emperor Manuel II Paleologus, regarding Islam, which several weeks after it was delivered, created violent reactions among Muslims in several parts of the world.
June 11, 2007 Pope Benedict XVI reverted the decision of his predecessor regarding papal elections,and restored the traditional two-thirds majority required 
October 28, 2007: Pope Benedict XVI authorizes the largest beatification ceremony in Church history involving 498 Spanish Martyrs who were killed during the Civil War in Spain.
May 2008: A solemn declaration agreed on between Pope Benedict XVI and Muslims, led by Mahdi Mostafavi, stressed that genuine religion is essentially non-violent and that violence can be justified neither by reason nor by faith.