An important thing to note about the cosmological arguments for God’s existence is that most of them don’t require a beginning of the universe. In one such argument, Gottfried Wilhelm von Leibniz famously offered God as an explanation for contingent reality.
He, in essence, posed the question “Why is there something, rather than nothing?”.
This has nothing to do with a beginning to the universe. It has to do with the fact that physical things are contingent. That is, it is logically possible for them not to have existed.
The trouble with this is that something which might not have existed, but does, needs an explanation for its existence. This is, among other things, a fundamental principle of science: that we can’t simply acquiesce to “just because”.
But, if we explain the contingent things in the universe with more contingent things, we’re still left with more explaining to do. The only way to avoid an infinite regress (and all the logical contradictions that would create) is if there were a necessary object which was the explanation of contingent reality.
That is, if there were something for which non-existence is logically impossible.
Whatever is great enough to both fully explain the vast network of physical objects that comprise the universe and exist of logical necessity would, at the very least, bear an uncanny resemblance to God. But, someone may argue, a key element of God is a certain amount of will. Could it not be that such a thing, great as it is, has no mind or will?
The short answer is “No, it could not”.
The long answer would reach far beyond the scope of this post, but a good summary would be the fact that a will, an ability to choose, is the most reasonable explanation for why a necessary object could produce a contingent universe.
After all, for the universe to simply emanate automatically out of its necessary cause (as Plato envisioned), would make the universe, and every particle in it, a necessary object.
So, while there is much more to be said, I think it is clearly more likely that God exists than that it is a logical contradiction for this universe to have one fewer quark than it has.
At the very least, the Platonist would owe us an argument in defense of that idea. And there are, indeed, other good arguments for God’s existence.