It seems like this is one of this author's absolute favorite arguments, and really...it's not a very good one. Here's a look at why.
1. Do you believe that the Universe expanded from a primordial hot and dense initial condition at some finite time in the past and continues to expand to this day?
Yes, I do.
2. Rewinding back to the origin of the Universe, how much matter can be put into zero spatial volume?
The answer, in my decidedly not-expert opinion, is that it doesn't matter (ha!). Matter formed after the initial expansion:
After inflation, the universe continued to grow, but at a slower rate. As space expanded, the universe cooled and matter formed.
(Side note: I thoroughly enjoyed the site I linked above! It's a really good primer.)
3. If a Supernatural Transcendent Causal Agent does NOT exist, what brought the Universe into existence?
The answer is really simple: We don't know.
But the answer to "I don't know" isn't "God"--indeed, that's a pretty terrible answer, and most theologians (again!) try to avoid the "God of the Gaps" argument. Centuries ago, people were asking, "If God didn't create man, what did? If God didn't create Earth, what did? If God didn't create the stars, what did?" Today, we have explanations for all of these phenomena that don't necessitate any supernatural explanation whatsoever.
We may or may not fully understand the birth of our universe at some point. We know more today than we have at any point in our history, and we learn more every single day, though, so I wouldn't argue that what we don't know equals a deity or deities.
4. Can you provide EMPIRICAL evidence for ANYTHING spontaneously appearing out of nowhere?
Once again, there's a pretty big presumption here: the premise that there was nothing and then there was something. In reality, there could have always been something--something different, perhaps, from what we have now, but still SOMETHING.
Indeed, if you really look at it, it's the same basic premise as religion, which says that God was there, and everything came from God. The only real difference is that science supports the idea that there is no need to resort to supernatural explanations before we've explored all of our natural possibilities.
5. What is your best explanation for the origins of intelligent life? Why?
Are we sure intelligent life is a thing? Have you seen our presidential election process this cycle...?
I kid, of course. My real explanation is pretty simple: a long slow progression of genetic variations culminating in intelligent life as we know it today.
Evolution is fact. I'm not going to debate it. It's supported by an overwhelming body of evidence from dozens of scientific disciplines. So instead, let me direct your attention to recent research indicating that income correlates with changes in brain structure.
What's the point? We know that brain structure is a critical factor in intelligence as we know it--and I stress as we know it because we can only define terms like intelligence in anthrocentric terms--and we know that changes in that structure can cause massive changes in behavior and cognitive abilities. It's not debatable. We know that the structure of the brain is also influenced by genetic factors. It simply makes sense that our brains themselves, the key to intelligent life as we know it, are the result of many millennia of evolution via natural selection.
I know I've said it before--in this post, in fact--but I really can't stress it enough:
The God of the Gaps is a terrible argument for the existence of a deity.
Here's how Theopedia--an encyclopedia catering to Biblical Christianity--defines this argument:
God of the Gaps arguments are a discredited and outmoded approach to apologetics, in which a gap in scientific knowledge is used as evidence for the existence of God.
Before the scientific revolution of the last four centuries, such arguments were commonplace and widely accepted, presumably because the "gaps" were large and showing no signs of shrinking. A lightning bolt crashes down, the peasants working in the field cross themselves and say "well, we don't understand that, so it must be God."
"If God didn't do it, who or what did?" We don't know, but we may very well know at some point in the future. Indeed, the bulk of the experiential evidence to date lands solidly on the side of us figuring it out.