You asked me:"Allow me to ask you a causal question along the same logical lines as you are using; if you believe that God caused the Universe, then what caused God?"
I've certainly pondered that, but the answer would be that God, being God, is eternal; otherwise, why bother with the concept of God?
The light bulb has finally gone off, and now I understand you. Because I have started with the assumption that something cannot come from nothing (and not a first principle) I cannot deduce an answer using logic. Fair enough. But if I may, let me ask you this: are not all your (and science's) first principles nothing more than assumptions themselves? After all, when you get right down to it, it is impossible to really be sure about anything; all first principles might derive from an elaborate illusion. You yourself may be a brain in a jar. Ultimately, reliance on first principles comes down to a matter of faith.
As a concluding aside, I don't necessarily have faith in God; if I did, I'd be a religious man. I simply cannot come up with a better explanation for the origin of the universe than God. It's not a belief so much as an exasperated shrug.
