…the Roman state periodically mandated persecutions, either to curtail or wipe out Christianity… The last two great persecutions were all-out assaults, total war against the Catholic Church; they aimed to destroy Christianity, root and branch.
The first was launched by the
Emperor Decius in A.D. 250, and an even greater one was unleashed by the
Emperor Diocletian in 303. Both were intended to be empire-wide, and both were carried forward determinedly for the better part of a decade. Holy books were confiscated and destroyed, churches were razed, and Christians were arrested and forced to offer pagan sacrifices on pain of torture and death.
When the Diocletian persecution finally proved to be a costly failure, the stage was set for the great reversal of policy by the Emperor Constantine in 313… Constantine had a dream that convinced him he would conquer in the “heavenly sign” of Jesus Christ (“In hoc signo vinces”)… the dream of Constantine meant that the emperor had come to believe in the God worshiped by the Christians.
This new conviction was to bring about a change in the attitude of the Roman state toward the Catholic Church… In March 313, Constantine and his co-emperor Licinius issued the
Edict of Milan… If the Empire could not succeed in destroying the Church, then the wisest policy was to attempt to enroll this far-flung, well-organized, and highly motivated-even if rather strange-new body as an ally…
This was the policy that Constantine and his successor Christian emperors sought to follow.