A religion whose adherents believe in or follow the religion of Jesus Christ. At first Christianity was simply a Jewish sect which believed that Jesus of Nazareth was the Messiah (or ‘Christ’, ‘anointed one’). Largely owing to the former Pharisee, Saul of Tarsus (later St Paul) it quickly became an independent, mainly gentile, organization. In the early centuries Christians experienced intermittent persecution by the state, though there was no clear legal basis for this until the reign of the Emperor Decius (ad 250). By the 3rd century, Christianity was widespread throughout the Roman Empire; in 313 Constantine ended persecution and in 380 Theodosius recognized it as the state religion. There were frequent disputes amongst Christians mainly over the status of Christ and the nature of the Trinity, and later over grace and Church organization. Division between East and West, in origin largely cultural and linguistic, intensified, culminating in the Schism of 1054, sealed by the Crusades. In the West the organization of the Church, focused on the Roman papacy, was fragmented by the Reformation of the 16th century. In the 20th century the ecumenical movement sought to heal these ancient rifts. The Protestant and Roman Catholic Churches are the main Christian denominations.

Christian fundamentalism is a Protestant religious movement that stresses traditional Christian doctrines, especially the literal truth of the Bible. Fundamentalism developed in the 1920s in opposition to modern techniques of biblical criticism; its adherents have been particularly powerful in the USA, especially among the various Baptist groups. Fundamentalists were and are particularly noted for their hostility to Charles Darwin’s theory of evolution, as shown by the prosecution of J. T. Scopes in Tennessee. Fundamentalism is associated with evangelicalism, and has re-emerged in recent years as an influential movement, particularly in the USA, where fundamentalist views reach a wide audience through religious broadcasting. Fundamentalists often have an uncompromising social agenda, which they see as traditionalist. This usually includes support for the criminalization of abortion and homosexuality, and insistence on the teaching of creationism (that is, the biblical account of the creation) rather than evolutionary theories in schools. Millenarian ideas rooted in biblical prophecies of the Second Coming have led to support for the state of Israel and for a strongly armed USA. US fundamentalists have been active missionaries, vigorously seeking to convert both non-religious people and adherents of other faiths. Similar movements are now found worldwide, among them the ‘House Church’ movement in Britain.