Quote Originally Posted by Sharad9 View Post
The world exists alongside a parallel reality that is equivalent to hell. This realm is filled with creatures called daemons that cross over into the world. The only thing keeping the daemons out is a thin barrier that exists between realms. This barrier is powered by human worship...

...How can I credibly describe how this church maintains its unity across a supercontinent without splintering?
Well, you've already described cheap, effective, long-distance methods of travel and communications controlled by the church- I don't see centralised administration of religious doctrine being a problem. The real question is how splintering could even occur.