I'm liking the 'priests write scrolls' idea. If a cult or church could suddenly summon a horde of monsters on your doorstep for being an unbeliever, you'd get yo ass to church.
If you gave religions a weapon, they'd have much more reason to fight. It would take some balancing measures and some testing, but I can't think of anything better than using the clergy to manifest power through the written word.
EDIT: Someone more familiar with making feature requests want to post this (and other ideas) so we don't hijack the thread?
If you haven't noticed, priests have no actual in game effects. This would be rejected instantly.
