Can you imagine a religion based on a dream of a murderer Emperor?
Yes, he dreamed of a cross in the sky, and desided this would be the symbol of the new religion
He killed his wife Faousta from Syria, his son Priscus, and his brother inlaw for not willing to change religion, on the behalf of his mother's will, Helen, and yet, they named him Saint Constantinus the "great" and Saint Helen, (murderers that is)
The Christian religion is based on books translated 1700 years ago on the request of Flavius Valerius Constantinus mostly from the Hebrew religion. Astonish me he said, write me a book for the new religion of the Empire.
Constantinus destroyed the Temple of Asklepius and killed all the priests. That was the begining of the destruction of the Hellenic world.
If there was an easy transition from the old religion to the new, then what in the world did they need these for? Records of the history of the church tell an other story, hiden from the world for 1700 years.