The issuance of the Edict of Milan is one of those moments in history of which everyone should be aware, so great were its consequences.
The Edict itself was drawn up in Milan by the Emperors Constantine I (of the West) and Licinius (of the East) in February of 313 and proclaimed in June 313 at Nicomedia. Following its formal announcement, the Edict was sent throughout the Roman Empire and its shock waves and ripple effects continue to our own day, even if these waters of change are beginning to be recede and, in some instances, being dammed up.
Building upon the Emperor Galerius' Edict of Toleration, which he issued in the year 311, that granted to Christians the tolerance "be Christians and may hold their conventicles [meetings or assemblies], provided they do nothing contrary to good order." The Edict of Milan went even further and granted "to the Christians and others full authority to observe that religion which each preferred." What is more, the Emperors Constantine I and Licinius declared:
Therefore, your Worship should know that it has pleased us to remove all conditions whatsoever, which were in the rescripts formerly given to you officially, concerning the Christians and now any one of these who wishes to observe Christian religion may do so freely and openly, without molestation. We thought it fit to commend these things most fully to your care that you may know that we have given to those Christians free and unrestricted opportunity of religious worship. When you see that this has been granted to them by us, your Worship will know that we have also conceded to other religions the right of open and free observance of their worship for the sake of the peace of our times, that each one may have the free opportunity to worship as he pleases ; this regulation is made we that we may not seem to detract from any dignity or any religion.In short, the Edict of Milan not only made Christianity a legal religion within the Roman Empire, but also restored to the Christians those properties which had been confiscated from them (why Constantine generally receives the credit for the edict and Licinius does not, I do not know).Moreover, in the case of the Christians especially we esteemed it best to order that if it happems anyone heretofore has bought from our treasury from anyone whatsoever, those places where they were previously accustomed to assemble, concerning which a certain decree had been made and a letter sent to you officially, the same shall be restored to the Christians without payment or any claim of recompense and without any kind of fraud or deception, Those, moreover, who have obtained the same by gift, are likewise to return them at once to the Christians. Besides, both those who have purchased and those who have secured them by gift, are to appeal to the vicar if they seek any recompense from our bounty, that they may be cared for through our clemency,. All this property ought to be delivered at once to the community of the Christians through your intercession, and without delay. And since these Christians are known to have possessed not only those places in which they were accustomed to assemble, but also other property, namely the churches, belonging to them as a corporation and not as individuals, all these things which we have included under the above law, you will order to be restored, without any hesitation or controversy at all, to these Christians, that is to say to the corporations and their conventicles: providing, of course, that the above arrangements be followed so that those who return the same without payment, as we have said, may hope for an indemnity from our bounty. In all these circumstances you ought to tender your most efficacious intervention to the community of the Christians, that our command may be carried into effect as quickly as possible, whereby, moreover, through our clemency, public order may be secured [more].
You will often find textbooks that claim Constantine I made Christianity the official religion of the Empire; this is simply false. Constantine I did not make Christianity the official religion of the Empire, but made it a legal religion in the Empire; a Christian could no longer be persecuted legally because of his faith in Jesus Christ.
It was the Emperor Theodosius I (r. 379-395) who, on 27 February 380, with his Edict of Thessalonica, made Christianity the "official" religion of the Roman Empire when he decreed that the citizens of the Empire "should continue to the profession of that religion which was delivered to the Romans by the divine Apostle Peter, as it has been preserved by faithful tradition and which is now professed by the Pontiff Damasus [r. 366-384]."
What is more, Theodosius I declared in the same document that those who did not profess the faith of the Apostle Peter "shall be branded with the ignominious name of heretics, and shall not presume to give their conventicles [meetings or assemblies] the name of churches."
How so many textbooks - written by those who claim to be historians - could confuse and conflate two key historical events separated by 67 years is beyond me.
It is curious how 1,700 years after a decree was issued that granted religious freedom to Christians that same freedom is now slowly - though increasingly - being stripped away from Christians.