Creating stories involving fantasy religions is fun and for some folks tricky. Religion is a large part of the human experience, and you lose some great story potential if you choose to omit religion from your world. This post is not about the deities themselves. Great stories are about conflict and the darker side of human nature, so with that in mind, let's proceed with some basic design choices, then get into the juicy bits with followers, dogmas, sin, heresy, redemption, and crusades.