Claims and counterclaims have been made since the idea was first postulated. Bertrand Russell said something simple but profound:
"...the Universe is just there, and that's all".Why cannot the Universe be infinite, regardless of whether we can comprehend that. We are after all just short lived carbon life forms living precariously on a small planet revolving around an unremarkable star.
We seem to be tantalisingly close to a scientific explanation for the origin of our Universe and the apparent "Big Bang" that started it all. But let's suppose that humankind is not able to fully understand the origin of the Universe, before our brief existence (In Cosmic terms) is snuffed out by our dying Sun. The fact that we do not understand something is not sufficient cause to say "God did it".
Let's imagine that every day my cat sees me taking food from the cupboard to feed him, but is never there when I replenish the cupboard. My cat has no idea why everything always comes from that cupboard or why it is there, but he knows that it does, he knows that it always has done, and has no reason to doubt that it always will. He has no facility to understand the process. But might it not seem reasonable to him that a God lives in the cupboard, a God which always provides, and apparently from nothing? There is a perfectly logical process, but he is mentally unequipped to understand it. As far as he is concerned I am the one who acts as an intercessor (I know how to open a can and he marvels at that!), and therefore perhaps I am the equivalent to his High Priest, if you like.
At a different scale and level of complexity, doesn't the God that humans assume exists fit the same mould? OK, so this is a gross oversimplification, but surely the basic prionciple is the same.