Angels and Demons

I was thinking whether I should write suggestive themes of angels and demons into a storyline I'm working on. In the Fantasy of War, I suggest that heaven and hell made a pact to never battle each other, as well as the fact that demons are pretty good people. :D Angels, are however, a little different. They are supposed to be a little unortodox, supposedly busy keeping the human world running, while demons keep the underworld running. The evil person is actually an angel (no surprise), but I bring the matter into more extreme hands, overthrowing the idea of one God being eternal and immortal. :D