I will prove to you that God exists

[Drew_2013]

Do you know of some force inside spacetime that caused spacetime to exist? We have mountains of evidence that natural forces came into existence. That tells us nothing about what caused them to exist or why the myriad of exacting properties and characteristics for life obtained.

All you're demonstrating is that in any epistemological system the root cause has to be treated specially.

Put more simply, if you keep asking "Why" long enough you get to a point where you can't easily find an answer. This is true for everybody regardless of belief. Here's how it goes:



Theist:
Q:Why does the universe exist?
A: Because of the Big Bang.
Q: Why does the Big Bang exist?
A: God made it.
Q: Why does God exist?
A: I don't know.

Both camps arrive at the same inevitable conclusion, but theists use an extra step that invokes an all-powerful supernatural entity for which there is no evidence and no possible explanation. That step has negative value for a long list of reasons. First and foremost, it cuts the throat of your argument with Occam's razor due to the addition of an infinitely complex and utterly inexplicable entity. It also prevents any further examination by terminating the chain of reasoning in the ineffable. Ending with "Goddunnit" means that mortal minds can inquire no further, which is why the last answer you'll frequently hear from theists isn't an honest "I don't know" but rather a "Die heretic!" By contrast, the atheist, and anybody looking to natural explanations for that matter, can end with, "I don't know yet, but we're still looking." That gets you out into the wilderness of speculative cosmology, but at least there isn't a priest holding a big sign reading "Thou shalt not ask!" The root cause may always terminate at "I don't know" but that's no excuse to stop trying to push back the boundaries.

Is this the best you can do make up a conversation between yourself...and yourself?

Why do laptops exist?
A. Because scientists, engineers and programmers collaborated to make a laptop exist.


A laptop which is simplicity in itself compared to the universe, requires an extra step as opposed to mindless natural forces accidentally causing a laptop to exist. Are there things which are beyond the capability of mindless natural forces? Fortunately we know how the virtual universe came into existence, once again it was the result of scientists, engineers and programmers using intelligence and intent to cause one to exist. Is it conceivable that mindless natural forces without plan, intent or a degree in engineering could somehow cause the virtual universe to exist? As an atheist you have to say its possible since according to atheists natural forces without plan or intent or an engineering degree to caused the real one to exist. 

Your other complaint is your mistaken belief that if a Creator caused the universe to exist that ends all scientific theory and inquiry. Isaac Newton considered the father of physics, believed there is a mathematical explanation for the movements of planets and celestial objects precisely because he believed the universe was intentionally caused to exist. He believed there was a creator, acted on it and as a result he uncovered many formulas and he's considered the father of physics. We know pyramids were intentionally caused to exist by intelligent beings, that doesn't stop scientists from figuring out how they Egyptians did it. Science won't stop tomorrow if they discover conclusive evidence our existence was intentionally caused. It will proceed as it always does. 

Theism is an explanation for why a universe came into existence and caused intelligent life to exist. Its not an explanation for why God exists. For that you need to speak to a theologian...which I am not.
 
Atheist
Q:Why does the universe exist?
A: Because of the Big Bang.
Q: Why does the Big Bang exist?
A: I don't know.

If that was truly your position (or the position of atheists) you'd say the claim it was intentionally caused to exist is as good as any other explanation since in fact we don't know. That's never the position of the atheist. It's true they don't know why the universe came to exist, however despite the admission of ignorance they believe it was unintentionally caused by mindless natural forces. In short Naturedidit.

I notice you're leaving multiverse out as a potential explanation presumably because it violates Occam's razor to infinity and beyond!