[Petrosius]

Constantine was the first Christian emperor, not a deified Caesar.

[j.havenfarm]

Off the top of my head I’d suggest the top heavyweights in the political development/ history of the west for good or for ill would be Cyrus, Alexander, Augustus, Constantine, Charlemagne, Locke/Montesque, Marx, and Hitler. Other nominees?

[verum ago]

Constantine was the first Christian emperor, not a deified Caesar.

He didn't start his reign as a Christian, though, he had converted by the time he converted the likeness on the statue from that of Maxentius to himself.

Interesting that he kept the Jupiter style for it, including at the time a beard (removed during a revamp over a decade later).