Even if there was a big bang with no corresponding big crunch, that's not a proof for God. It has been established that certain particles can "pop" into existence out of "nothing". Mind you they don't last very long, but it proves the principle that nature abhors a vaccuum.
Also there's the circular reasoning argument, which begs the question who or what created God?
Then there's the cultural bias. How do you know it's the Abrahamic god that created the cosmos and not a different deity?
Hmm interesting so certain particles can "pop" into existence out of nothing?
Please give reference here, purely for the sake of completeness.
Now, regarding that statement, what makes people think that they "popped" out of nothing? One of the interesting things about certain particles is that "tachyons" for example or "neutrinos" also seem to be able to "pop" into existence without evidence of causality, but then again such "hypothetical particles" if they did in fact break or bend around the light speed barrier, could theoretically travel into the past and thus seem to "pop" into existence....