In contrast, Constantine himself apparently liked to tell stories about his many visions and conversion experiences. Consideration of only these three episodes suggests that Constantine may have had many conversion moments, and that his religious beliefs throughout his reign were not as consistent as Eusebius presented them. Despite his evident patronage of Christianity, his life included changes of mind, uncertainties, contradictions, and ambiguities. In other words, it was anormal life. (p 137.)
Apparently he requested that a giant statue of himself at Rome should hold a cross in its right hand, and that the dedicatory inscription should commemorate his devotion to the Savior: "I have liberated your city by this sign of salvation." In contrast, the dedicatory inscription on the huge triumphal arch completed at Rome in 315 was much more bland and noncommittal. It attributed Constantine's success merely to "the impulse of a divinity." (p136)
That he was baptised as one of the last things he went through in life seems uncontroversial. Whether he was old Roman pagan, Mithraist, Arian, Nicean creed Christian in terms of true belief seems hard to ascertain for any one point in time and even more uncertain for a stringent line of his life. Instead, one thing seems very certain, that has was a politician.