Suppose the concept of God wasn’t eternal. There was some mechanism, perhaps even simpler than God, that gave rise to His existence. Is this more or less plausible than Him eternally existing?
What about God springing out of nothing? If God had a beginning but with no cause, would this be more or less plausible than Him eternally existing?
How should eternity affect how plausible the existence of an agent is? Is this a philosophical question or an empirical question for physicists?