The following year, together with Eastern Roman Emperor Licinius, he issued the Edict of Milan, which for the first time gave freedom of worship to Christians.
Thus we find one Protestant polemicist, Pierre Dumoulin, insisting that the Edict of Nantes was not even necessary because the king could count on unconditional obedience.
Christianity finally became the state religion in 380, when Emperor Theodosius I issued the Edict of Thessalonica, which ordered everyone in the empire to become Christian.
The Edict of Thessalonica was so significant that it was listed in 529 as the first item in Emperor Justinian's comprehensive collection of imperial laws, the Codex Justinianus.