That's because Supersititious is buggy.

It *should* only happen at birth or when surviving a natural disaster, but for some reason the natural disaster trigger fires randomly. Which is also why you can get "Conforming" generals out of the blue, because ForcedReligious is also triggered by that one.

And no, I have no idea why. My guess is that the trigger is fired whenever there is a character damaged by a disaster ANYWHERE in the world.