Stump the Christian?

[Esquilax]

You're talking about the beginning of space-time. That question makes as much sense as this: "What lies to the north of the north pole?!?"

If absolutely nothing existed prior to the Big Bang, why did it happen and where did all this "stuff" come from?

He didn't say nothing existed prior to the big bang. He implied, I think, that space and time as we understand it began at the big bang; asking what happened before that point is attempting to extend our current causal framework back before it existed, which is a nonsensical idea. The short version is that we don't know what came before, or even if "before" is a concept that means anything; we are discussing a form of reality that is like nothing we have ever experienced, that literally lies outside of anything we have ever known, that requires a completely different language to discuss the concepts we might find there, as our language is necessarily temporal in its construction. You're probably not even asking the right question; there's a very real possibility that it's impossible for you to ask the right question in a currently extant form of language.

Now, I do have a question: you asked this question about what lies before the big bang in response to a post that asserted that saying evolution concerns life coming from nothing is a misrepresentation. I think I know what ridiculous point you're getting at there, but I figured I'd ask first: why did you do that?