Well I don't know what's the timeline for the decay? I can't seem to make it far out of BC because I just kill everyone. Maybe if I made it to late game I would notice it? Also I never change my state religion, I just don't see the benefit. But I tend to spread a few religions around, usually 3-4 on my home continent.
I do like the idea of ancient religions that go obsolete. Also perhaps some sort of culture upkeep for religious buildings?
I do like the idea of ancient religions that go obsolete. Also perhaps some sort of culture upkeep for religious buildings?