Which ruler was responsible for granting religious freedom to all romans?

In 313 AD, shortly after the end of the persecution of Christians by the emperor Diocletian, Western Roman Emperor Constantine I and Licinius (who controlled the Balkans) issued the Edict of Milan, which granted religious freedom to all. It was a letter signed by the Roman emperors proclaiming religious toleration in the Roman Empire. It gave Christianity a legal status, but did not make Christianity the official religion of the Roman Empire. It did, however, end religious persecution in the Roman Empire.