What was the importance of the Edict of Milan?

The Edict of Milan was promulgated in Milan in the year 313. It established freedom of religion in the Roman Empire, ending the persecution directed by the authorities against certain religious groups, particularly Christians. The edict was signed by Constantine I the Great and Licinius, leaders of the Roman empires of the West and East, respectively.

At the time of the promulgation of the edict, five to seven million inhabitants of the fifty who made up the Roman Empire professed Christianity.