pondering paper topics

Do any of y'all know of speculative fiction/scifi/fantasy novels that involve multiple faiths? I seem to be able to name ones that have One Big Church but an imagined world with multiple faiths isn't quickly jumping to mind. I must be missing something.

ETA: Wow. I must have had my brain turned off not to remember Small Gods. Thank you guys so much for these! (Now I have new reading material that doesn't involve the word "discourse"!)