Christianity, religion founded in Palestine by the followers of Jesus. One of the world's major religions, it predominates in Europe and the Americas, where it has been a powerful historical force and cultural influence, but it also claims adherents in virtually every country of the world.
The central teachings of traditional Christianity are that Jesus is the Son of God, the second person of the Trinity of God the Father, the Son, and the Holy Spirit; that his life on earth, his crucifixion, resurrection, and ascension into heaven are proof of God's love for humanity and God's forgiveness of human sins; and that by faith in Jesus one may attain salvation and eternal life (see creed). This teaching is embodied in the Bible, specifically in the New Testament, but Christians accept also the Old Testament as sacred and authoritative Scripture.
Christian ethics derive to a large extent from the Jewish tradition as presented in the Old Testament, particularly the Ten Commandments, but with some difference of interpretation based on the practice and teachings of Jesus. Christianity may be further generally defined in terms of its practice of corporate worship and rites that usually include the use of sacraments and that are usually conducted by trained clergy within organized churches. There are, however, many different forms of worship, many interpretations of the role of the organized clergy, and many variations in polity and church organization within Christianity.
Divisions within the Religion
In the two millennia of its history Christianity has been divided by schism and roiled by heresy, based on doctrinal and organizational differences. Today there are three broad divisions, Roman Catholic, Orthodox Eastern, and Protestant; but within the category of Protestantism, there is a particularly large number of divergent denominations. Because of the complexity of these differences this article will describe the history of Christianity only to 1054, when the schism between Eastern and Western churches became final. Separate articles detail the history and doctrines of the Roman Catholic Church and Orthodox Eastern Church and of the other churches of ancient origin, the Armenian Church, the Coptic Church (see Copts), the Jacobite Church, and the Nestorian Church. In the 16th cent. another major schism took place in the Western Church with the Protestant Reformation. For the Protestant churches, see Protestantism and articles on the separate churches. For the 20th-century movement that seeks to end the divisiveness in Christianity and achieve reunion, see ecumenical movement.
Christianity is in a direct sense an offshoot of Judaism, because Jesus and his immediate followers were Jews living in Palestine and Jesus was believed by his followers to have fulfilled the Old Testament prophecies of the Messiah. Following a trend of proselytization in the Judaism of that period Christianity was from its beginnings expansionist. Its early missionaries (the most notable of whom was St. Paul, who was also responsible for the formulation of elements of Christian doctrine) spread its teachings in Asia Minor, Alexandria, Greece, and Rome. Missions have remained a major element in Christianity to the present day.
For the first three centuries of Christianity, history is dependent on apologetic and religious writings; there are no chronicles (see patristic literature). Historians differ greatly on how far back the 4th-century picture of the church (which is quite clear) can be projected, especially respecting organization by bishops (each bishop a monarch in the church of his city), celebration of a liturgy entailing a sacrament and a sacrifice, and claims by the bishop of Rome to be head of all the churches (see papacy). There is evidence for these features in the 2d cent. A first problem for Christians was how to resist attempts to interpret the new beliefs in pagan terms (e.g., Gnosticism). The earliest sectarian deviations were those of Marcion and of Montanus (2d cent.). They were handled resolutely by the church; the teachers of novelty were expelled (excommunicated).
For 250 years it was a martyrs' church; the persecutions were fueled by the refusal of Christians to worship the state and the Roman emperor. There were persecutions under Nero, Domitian, Trajan and the other Antonines, Maximin, Decius, Valerian, and Diocletian and Galerius; Decius ordered the first official persecution in 250. In 313, Constantine I and Licinius announced toleration of Christianity in the Edict of Milan. In the East the church passed from persecution directly to imperial control (caesaropapism), inaugurated by Constantine, enshrined later in Justinian's laws, and always a problem for the Orthodox churches. In the West the church remained independent because of the weakness of the emperor and the well-established authority of the bishop of Rome.
Controversy and Growth
For 300 years after AD 275 the church in the East was occupied with doctrinal controversies—Arianism, Nestorianism, Monophysitism, and Monotheletism. These arguments concerned the manner in which Jesus is both divine and human. Decisions were made at a series of general councils of bishops (see council, ecumenical); at them was composed the Nicene Creed. These centuries saw a series of Christian writers of unequaled influence (the Fathers of the Church): Origen, St. Athanasius, St. Basil the Great, St. Gregory of Nyssa, St. Gregory Nazianzen, St. John Chrysostom, and Theodoret writing in Greek; St. Ambrose, St. Jerome, and St. Augustine writing in Latin. Origen and St. Jerome had a special role in the church's work of determining and preserving the text of the Bible.
From the 3d cent. monasticism was one element of the church. It was first organized by St. Basil. In the West monasticism was central to the missionary work of St. Martin (Gaul, 4th cent.) and St. Patrick (Ireland, 5th cent.). It received definitive shape from St. Benedict and St. Gregory the Great, who thereby generated a mode of life of continuing vitality in the Roman Catholic Church.
German invasions slowed the conversion of Western Europe (e.g., that of England was recommenced in the 6th cent.). Most of the first invaders were converted to Arian Christianity, but the pagan Franks (with Clovis) adopted orthodox Christianity, a fact that probably helped to consolidate their rule. Out of this kingdom came Pepin and Charlemagne, who, by alliance with the papacy and proclamation of an empire (800), charted an ideal of the Middle Ages.
Schism between East and West
In the 7th and 8th cent. the Eastern Church lost to Islam all Asia except Asia Minor. Alienation from the West was exacerbated by the bitter struggle over iconoclasm; ecclesiastical animosity between Rome and Constantinople came to a head in the schism of the 9th cent. This schism centered on the addition of the Filioque to the Nicene Creed (see creed) in the West and on the western church's use of unleavened bread in the celebration of the mass and insistence on clerical celibacy. The division between East and West grew wider and attained a sort of legal permanence in 1054 (see Leo IX, Saint). Eastern and Western Christendom were already in the 9th cent. two different cultures; their one common tie was the Christian doctrine—even worship and practices were very different. From this time it is customary to distinguish Christian history in its Eastern and Western streams as that of the Orthodox Eastern Church and Roman Catholic Church.
See J. Lebreton and J. Zeiller, A History of the Early Church (4 vol., 1944–46; repr. 1962); H. Lietzmann, The History of the Early Church (4 vol., tr. 1961; repr. 1967); A. Finkel, The Pharisees and the Teacher of Nazareth (1964); H. Marrou et al., The Christian Centuries (1964); J. G. Davies, The Early Christian Church (1965); H. Chadwick, The Early Church (1967); R. M. Grant, Augustus to Constantine (1970); R. W. Southern, Western Society and the Church in the Middle Ages (1970); R. Fletcher, The Barbarian Conversion (1998); D. MacCulloch, Christianity: The First Three Thousand Years (2010); G. Vermes, Christian Beginnings: From Nazareth to Nicaea (2012); R. L. Wilken, The First Thousand Years: A Global History of Christianity (2012).