...Because they were convenient for a Roman Emperor to unite a failing empire. They had big armies and thus managed to force lots of people to follow the new nonsense. The lands that were forced to convert then went on with big armies to force loads more.
So you see, it is all perfectly rational - truth comes from a big sword. (said in irony).
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.