I suppose the theist would want to claim that the nature of God is such that he/she/it wasn't created. I take it that theists regard God as ontologically quite distinct from ordinary beings in that God supposedly is not dependent on anything else for his/ its existence. Kind of like the old philosophical notion of substance. I don't think there is anything conceptually incoherent about that. Indeed, for God to require something else for its existence would defeat the very notion of the God that theists want to posit, methinks. I don't know. Maybe I'm just rambling. It's late and I'm tired.