Christianity originated from the Jewish community in the Jewish province of the Roman Empire (present-day Israel and Palestine) in the/kloc-0 th century. Before the end of the first century, it gradually developed to Syria, Egypt and Asia Minor, and extended to Greece and Italy. Christianity was persecuted until the 4th century, when Constantine the Great promulgated the Milan Decree (3 13) and declared it as a legal religion. In 380, Theodosius I declared Christianity the state religion of the Roman Empire. Everyone should believe it. During the period of 1054, there was a great division in Christianity, with the Eastern Church calling itself the Orthodox Church and the Western Church calling itself the Catholic Church. Protestantism and many other small sects split from Catholicism in the16th century.