Which Roman Emperor who ruled from 300-377 AD was the first to be converted to Christianity?
Constantine the Great and Christianity Constantine the Great and Christianity During the reign of the Roman Emperor Constantine the Great (AD 306–337), Christianity began to transition to the dominant religion of the Roman Empire. Historians remain uncertain about Constantine's reasons for favoring Christianity, and theologians and historians have often argued about which form of early Christianity he subscribed to. There is no consensus among scholars as to whether he adopted his mother Helena's Christianity in his youth, or, as claimed by Eusebius of Caesarea, encouraged her to convert to the faith he had adopted himself. Constantine ruled the Roman Empire as sole emperor for the
Holy Roman Emperor with very few exceptions, taken on a role as promoters and defenders of Christianity . The title of "Emperor" became defunct in Western Europe after the death of Julius Nepos in AD 480, although the rulers of the barbarian kingdoms continued to recognize the Eastern Emperor at least nominally well into the 6th century; both the title and connection between Emperor and Church continued in the Eastern Roman Empire until 1453, when it fell to the forces of the Ottoman Empire. In the west, the title of Emperor ("") was revived in 800, which also renewed ideas of imperial–papal cooperation.