Whatever we find in reality, it is not dubious at all since not only was it possible, it literally is actual. To say something about reality is dubious without God — the existence of morality, logic, math, butterbeer — because it must have some grander explanation is dubious. The most dubious sort of “grander” is of course, “god”; a being which lay completely outside our ordinary experience and our ability to conceive of, even our ability to say exists. And it must be “god” because anything else is still too ordinary! Yet so “grand” is “god” that by definition, he cannot be related to reality at all, especially to say that without “god”, something in or about reality is impossible, though again, it is the only thing in such a conversation that is actual at all.
If there is no means by which we can tell the difference between a universe with God and a universe without God, then God is all that can be said to be dubious and nothing else, no matter how queer or long the odds for any fact of the matter in reality.