I later realized: you can cut all that.
People get the basics. They know what "the rapture" is. The book sold 65 million copies and the theological background is now common pop-culture knowledge.
People who watched The Simpsons understood enough to get the joke. So people who read academic work about evangelical fiction get enough to follow an argument.
Lesson: it's OK to trust your readers a little bit. They know a couple of things.