I didn't say their wouldn't be a alternate Christanity.
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"Of mortal men none can look upon the direct brilliance of O'Lord Sun!
Except! One! One so divinely favored to rule and rules all! Who be this?
It is Constantinius Augustus! Watch as he gathers all true Romans into the embrace the divine!"- Attributed to Titinius
Some have said that at one point the Emperor himself was swayed by the word of the Christian God and that until his death he had worked on divine inspiration from the Christ. This of course is quite unlikely and as pompous as the assertion by Solarians that he received divine visions from Sol! In the mind of Constantine there was only great being on this earth and that was himself, which eventually became more and more inflated as he united the Roman Empire from the fractured Tetrarchy, though one should not doubt that nonetheless Constantine like all Romans at this point was quite superstitious and practical-if a god favored him he would repay them back in full to continue this favor. Opportunities again and again presented him opportunity to work on this such as at his entrance into Rome and the commemoration of the Arch of Constantine where he loudly trumpeted his thanks to victory to the Invincible Sun, a very blatant play to the pagan majority of the Roman Empire. The Edict of Milan is why most sects of the Christians consider him a saint or a hero of Christianity (not unlike the persistent myth of Alexander the Great being a hero to the Jews) as the persecutions of Diocletian were quite fresh in the collective mind of that volatile faith. Given that the territories of Licinius contained the largest portion of Christians in the Roman Empire Constantine was more than happy to play himself off as a savior following Licinius’s persecutions of the Christians to improve his position as he united the Roman Empire once more.
It had long been a standing view in the empire that peace in the empire came from peace of the gods, and thus in these particularly violent and changing times Constantine sought to maintain the Empire on part by bringing under his civil and religious authority all of the religions. It was as it were the escalating violence between the various Christian sects that turned him away from the Christian faith and attempts to arbitrate between the various creeds ended in frustration and refused to favor any sect in giving them high positions of power and rule in Rome or throughout the eastern provinces. Though of all it was the sermons of the future Pontifex Maximus Titinus that caught his attention in 59 SE just before the commemoration of his city, Constantinople.
Titinius was the son of a soldier in Constantine’s army that had fought its way from Britannia to Rome and had settled in Rome in 41 SE and who was known as a initiate of the Cult of Mithras which was quite popular amongst the army. Growing up in Rome, Titinius encountered perhaps all the religious creeds that inhabited the Roman Empire and most likely from this gradually what would become the doctrine of the Cult of Sol emerged. Taking from the already well established Cult of the Sol, the Oriental Faiths such as Mithras and Isis, the classical Roman religion, the philosopher faiths such as that from Plotinus and Stoicism, and even Christianity and Judaism in a synergetic faith. His oration and eloquence easily drew crowds by the hundreds in Rome as he emanated what was described as an infectious passion. He announced that eternal life and peace in this world and the next was possible through embracing the rule of the Sun. What was crucial to Constantine though in that Titinius showered high praise on Constantine, proclaiming him favored by Sol, and by extension all gods, to rule on this earth.
A faith that supported his rule and the absorption of the various faiths into a manageable order was something that more than likely very interested Constantine. Perhaps if there is any truth to the legend that Apollo ordained his rule in Gaul or Sol outside of Rome then he may have been influenced by this. The motivation for declaring Constantinople’s nickname the City of the Sun or Heliopolis was possible rooted in his exhaustion of the infighting amongst the Christian sects or perhaps he did see Sol as favoring him or more likely was showing off his divinely favored credentials once again. Whatever the reason, Constantine was considered The Great by all faiths of the Empire at the time but his successors would not be as restrained.
-The Total History of the Roman Empire (1766 SE)