There are some attempted explanations for the theoretical inflationary phase of the big bang, but nothing I'm aware of that's been nailed down yet by experimental evidence. Physicist can expand on this if he's so inclined. However, you raise a very important philosophical issue. We have here a physical phenomenon (the big bang) which is not yet explained. (It's a very difficult problem, and it's certainly not explained to my satisfaction.) You, and a great many others, latch onto that as a "mystery" which is "proof" for the existence of God. But to me it is no such thing.
An unsolved problem doesn't prove anything about God. All that it demonstrates is that we don't yet have all the answers, which is hardly a controversial point. Whenever such "unknowns" take on the mystical aura of divinity, a terrible conflict is unnecessarily created between those who want to learn more about the physical phenomenon and those who assert that such intellectual inquiry is blasphemy. So that attitude -- that unknowns are "proof" of God -- gives science a hard time; and if the question is eventually answered -- as so many unknowns have previously yielded to scientific inquiry -- it makes the theologians look foolish.
I think the origin of the big bang is more significant than an "unsolved problem". We must account for the existance of the universe in a logical way. The big bang theory takes us back to a sigularity, but does not provide the motive power for the "inflation" of the universe. Nor does it explain the fine structure of the universe.
My definition of "proof" is a "convincing argument". I well know that different people are convinced by different arguments. The theory of a Divine origin of the universe fits the available facts than any other explanation I saw at that time (1969). I haven't seen a better explanation since then, and I have had independent confirmation of the existance of God since then.
It is primarily an unsolved problem. In addition to that, for many people, it has taken on an emotional, mystical significance which goes way beyond the scope of science. But as a scientific issue it's like any other (but far more difficult to work on).
My definition of "proof" is a "convincing argument". I well know that different people are convinced by different arguments. The theory of a Divine origin of the universe fits the available facts than any other explanation I saw at that time (1969). I haven't seen a better explanation since then, and I have had independent confirmation of the existance of God since then.
If you truly had a "convincing argument" it would do what you think it ought to do -- it would convince people. But if your theory of divine origin convinces only people who want to be convinced, and it leaves skeptics un-convinced, then you should realize that your argument isn't very convincing.
I am interested in your "independent confirmation of the existance of God". If you have verifiable evidence, I hope you will present it to us so that all may have the benefit of this confirmation.