The acceptance by Constantine the Great in 313 of Christianity as a legal religion within the Roman Imperium was a truly revolutionary event.
The New England theologian Jonathan Edwards, in A History of the Work of Redemption, was convinced that Constantine’s “great revolution” was “like Christ’s appearing in the clouds of heaven to save His people and judge the world.” It was, in Edwards’ fulsome words: “the greatest revolution and change in the face of things on the face of the earth that ever came to pass in the world since the flood. Satan, the prince of darkness, that king and god of the heathen world, was cast out; the roaring lion was conquered by the Lamb of God in the strongest dominion that ever he had, even the Roman empire”.
Whether or not one agrees with Edwards here, there is little doubt that the Constantinian revolution was a turning-point in church history.