Roman emperor Julian was nicknamed “the Apostate” because he rejected Christianity and attempted to restore traditional Roman religion.
Julian became emperor in 361 CE after serving as Caesar under Constantius II. He had been raised as a Christian, but later studied Greek philosophy and adopted traditional religious practices. His reign lasted less than two years, yet his religious policy made him one of late Rome’s most distinctive rulers.
Julian reopened pagan temples, supported traditional sacrifices, and limited Christian privileges in education and administration. He did not completely suppress Christianity, and Christians remained a large and influential part of the empire. His successor, Jovian, quickly reversed much of this policy.
The nickname “the Apostate” was mainly used by Christian writers hostile to Julian. Julian is also remembered for his campaign against the Sasanian Empire, during which he died in 363 CE near Ctesiphon.