One thing that doesn't really make sense to me about this argument: how can a wholly necessary being be the explanation for contingent facts? Certainly any

purely logical inference from a set of necessarily-true propositions (say, propositions about God and/or mathematics) would also be a necessary truth. To

quote Time Bandits, a theist might say "I think it's something to do with free will", but in this context the concept of free will just seems like a non-explanation, or something we're supposed to accept as a "mystery" that defies any rational understanding.

Another possible flaw in the argument: we don't actually

know that any facts about the universe are ultimately contingent! I have a fondness for physicists Max Tegmark's semi-philosophical

Mathematical Universe Hypothesis, which supposes that mathematical platonism is true and that our physical universe is just one of the infinite set of mathematical structures (as physics describes it in a purely mathematical way), and that any mathematical structure complex enough to contain self-aware information-processing systems will seem equally real and "physical" to its inhabitants. If this were true, all facts about the our universe would be just as necessary as any other mathematical truth. Some philosophers have suggested something similar, I think Spinoza endorsed the idea that all truths were necessary ones for example.