DR Laura, I don't know the legal answer in Arizona, so this isn't legal advice. But it wouldn't hurt to ask him if he's done with it. Maybe he will just give it to you and then there isn't anything to worry about. You could always say you noticed he had all of his belongings out of the church so you were just wondering if there was any reason he may still need the keys and if not, that it may just be easier for everyone if he would give them back now.
I don't know what the answer is if he says no, but if he has no interest in going back to the church, he will probably just give them to you