My two cents:
I think that there are certain branches of Christianity that have a strong internal mythology that requires a cast of sinners, demons and devils to cast out and exclude.
Imagine these same flavours of Christianity suddenly plunged into and then attempting to exist in a world where there were NO bad things -- no homos, no sexual predators, no terrorists, everybody perfectly good and moral, and everybody WILL go to heaven. I do believe it would drive them crazy...
Karen