State church
In 313 the Edict of Milan legalised Christianity alongside other religions allowed in the Roman Empire. In 325 the First Council of Nicaea signalled consolidation of Christianity under an orthodoxy endorsed by Constantine, and though this did not make other Christian groups outside the adopted definition illegal, the dissenting Arian bishops were initially exiled. But Constantine reinstated Arius just before the heresiarch died in 336 and exiled the Orthodox Athanasius of Alexandria from 335 to 337. In 380 Emperor Theodosius I made Christianity the Roman Empire's official religion (see State church of the Roman Empire, Byzantine Empire and the Goths) and did enforce the edict. In 392 Theodosius passed legislation prohibiting all pagan cultic worship.