Ultimately, I think the majority of confusion on this matter arises from the fact that Christianity became the State religion during the time of Constantine, and this presented a major problem for all the Pagan religions at the time. They needed to adjust their religious system to accommodate Christianity or face serious repercussions.

Enter Catholicism...

Catholicism is the main culprit for merging Paganism into Christianity, not Constantine.

Satan basically said, "I can't beat/kill the Christians. Might as well join them!"

Ultimately, I think the majority of confusion on this matter arises from the fact that Christianity became the State religion during the time of Constantine, and this presented a major problem for all the Pagan religions at the time. They needed to adjust their religious system to accommodate Christianity or face serious repercussions.

Enter Catholicism...

Ultimately, Catholicism is the main culprit for merging Paganism into Christianity, not Constantine.

Satan basically said, "I can't beat/kill the Christians. Might as well join them!"