مرسوم ميلانو
The city continued to expand and became a significant political and economical centre, more so as it became one of the first Roman cities where Christianity was recognised as an official religion. The Edict of Toleration was issued in 311 in Serdica by the Roman emperor Galerius, officially ending the Diocletianic persecution of Christianity. The Edict implicitly granted Christianity the status of "religio licita", a worship recognized and accepted by the Roman Empire. It was the first edict legalising Christianity, preceding the Edict of Milan by two years. Moreover, in the Edict of Milan, only one sentence was dropped: “Ne quid contra disciplinam agent.” So the Edict of Milan preached unconditional religious tolerance where the Edict of Serdica stated a conditional tolerance (meaning of disciplinam here is: unless they, the christians, disturb the good or social order of the State).