What was Constantine’s Christianity like?

I read an article saying how it was undeniable that Constantine did convert, but the only question was which type of Christianity did he pursue? It stated Christianity of the time was a very loose organisation, without particularly defined universal doctrine. I think its too easy to look at ‘Christianity’ in a uniformitarian way, and that we are talking about a religion similar to that which is practiced in the world today, when in reality it was probably quite different.