I agree. I do a lot of work to justify my worldbuilding, and gods aren't locked in to a contract regardless of what their clerics do. You can still have a schism or heresy, its just doctrinal as opposed to divine. Who says there aren't multiple ways a god will accept worship? The mortals in question, however, may not agree.
If someone betrays Athea, the goddess of nonbelief, she instantly robs them of any powers they might have--and she knows, instantaneously, of the betrayal, so there is zero time between "someone has broken faith with me" and "I have shut down all troublemakers." That is literally the text of the rules in 3e.
You cannot have, for example, a disagreement about whether Bahamut prefers law over good or good over law. He will instantly know what the disagreement is, and he will assuredly have a position, and declare at least one of the factions in error. Any such persons will instantly be stripped of any and all powers derived from him, for exactly as long as they remain in error. He can, of course, change his mind at any time, but presumably he would wait until the moment they have shown true contrition (which, again, he can instantly know because of how 3e divinity works), and then the power instantly comes back on again.
There can be no possibility of a genuine doctrinal disagreement, because anyone who actually strays is instantly depowered, and losing your powers is a
pretty flippin obvious reason for people to decide you're dead wrong.
You can't have secret traitors pretending to be faithful. You can't have honest-mistake zealots believing that they're doing the right thing while actually committing horrible evils. You can't even really have heterodoxy, because the deity herself can simply pop in and clarify exactly what they want, and anyone who continues to disobey, well, they were told what was correct, time to cut them off from the divine credit card.