History tells us how The Good Book came about.
It also tells us how it survived.
Without Constantine the religion may not have survived at all.
Constantine's story about the vision, similar to St Paul's, and what happened afterwards, is somewhat reminiscent of the stories in Daniel in the Bible. And we read about it in history, not in the Bible.
It looks very much like Jesus chose Constantine similar to St. Paul. Both of them have had a huge impact on Christianity, the same as Jesus himself.