The Emperor Constantine issued the Edict of Milan and accepted christianity.
Step-by-step explanation:
Constantine was the first emperor to convert to christianity. He played an efficient role in proclamation of the Edict of Milan and accepted christianity.
Churches were built in Rome and throughout the Empire. Constantine's decision is sometimes referred to as Triumph of the church, peace of the church, the constantinan shift.
He became a great patron and served as a saint in the Eastern Orthodox church and Oriented Orthodox church as Christian monarch.