Imagine an eloquence bard doing the televangelist thing and leading worshippers of a deity away from that deity. Deity can't even take the bard's spells away, because they aren't divinely granted. This bard could fake like he's a cleric for quite some time, even learning healing spells to help maintain the lie.

I mean, sooner or later the clerics of that faith are going to come calling with actual divinely granted powers, but that bard can put a lot of warm bodies between the clerics and himself