ミラノ勅令
The Roman church was a small community, and its bishop exercised little influence outside its members in the time of Constantine. Constantine was the first Roman Emperor to embrace Christianity, although he likely continued in his pre-Christian beliefs. He and co-Emperor Licinius bestowed imperial favor on Christianity through the Edict of Milan promulgated in 313. After the Edict of Milan, the church adopted the same governmental structure as the Empire: geographical provinces ruled by bishops. These bishops of important cities (Metropolitan bishops) therefore rose in power over the bishops of lesser cities (later called Suffragan bishops).