The fact that the claims of theism were simply unknowable, and that theism's advocates were claiming knowledge of things they couldn't possibly know.
Are you saying that not a single advocate for theism admitted, right up front, that at the core is nothing more than faith?
You’ve just met the first advocate that admits this up front.
The rest of it is circumstantial evidence, the crushing weight of the improbability of the Universe and everything in it being a random act, etc.
But, at the core, there is belief, not fact.
I can’t know this, of course, but in looking back are you sure that none, no one, admitted up front that everything about God, or a supreme being, is about faith?