The history of Christianity begins with the ministry of Jesus, a Jewish teacher and healer who was crucified and died c. AD 30–33 in Jerusalem in the Roman province of Judea. Afterwards, his followers, a set of apocalyptic Jews, proclaimed him risen from the dead. Christianity began as a Jewish sect and remained so for centuries in some locations, diverging gradually from Judaism over doctrinal, social and historical differences. In spite of the persecution of Christians in the Roman Empire, the faith spread as a grassroots movement that by the third century was established both in and outside the empire. New Testament texts were written and church government was loosely organized in its first centuries, though the biblical canon did not become official until 382. Constantine the Great was the first Roman Emperor to declare himself a Christian. In 313, he issued the Edict of Milan expressing tolerance for all religions. He did not make Christianity the state religion, but he did provide it with crucial support. Constantine called the first of seven ecumenical councils. In the fourth century, Eastern and Western Christianity began to diverge. Between 600 and 750, the constant need to defend itself in war turned the Eastern Roman (Byzantine) Empire into an independent polity. Missionary activities spread Christianity across western Europe. Monks and nuns were prominent in establishing a Christendom that influenced every aspect of medieval life. From the ninth century into the twelfth, politicization and Christianization went hand-in-hand in developing East-Central Europe. Byzantine Christianity influenced the church, culture, language, literacy, and literature of the Slavic countries and Russia. During the High Middle Ages, Eastern and Western Christianity had grown far enough apart that differences led to the East–West Schism of 1054. Temporary reunion was not achieved until the year before the fall of Constantinople in 1453. The fall of the Byzantine Empire ended the institutional Christian Church in the East as established under Constantine, though it survived in an altered form. Various catastrophic circumstances, combined with growing criticism of the Catholic Church in the 1300–1500s, led to the Protestant Reformation and its related reform movements. Reform, and the Catholic Counter-Reformation, were followed by the European wars of religion, the development of modern political concepts of tolerance, and the Age of Enlightenment. Christianity also influenced the New World. After World War II, Christianity faced many challenges. Traditional Christianity declined in the West, while new forms developed, and the centre of growth shifted from West to East and from the North to the Global South. In the twenty first century, it is the world's largest religion with more than two billion Christians worldwide. Source: Wikipedia (en)