Just a quick clarification, then, about my argument. If you're looking for an atheistic final and complete explanation of everything, you'd be open yourself to the theist's move of identifying the ultimate, self-creating constituents of matter (the quantum foam, Big Bang singularity, multiverse inflation, etc) with God.

That's the problem. The explanations would have to stop at a virtual absolute which would function as God--not as an old man with a gray beard in the sky, but as an awe-inspiring, eternal, all-creative ground of being. The completion of explanation seems to preclude atheism, given the philosopher's depersonalized, mystical conception of divinity.