It's not like it's impossible to disprove.
Actually, it pretty much
is impossible to disprove a being who can do literally anything. This is how you have some young-earth creationists saying things like "dinosaur bones were just put there to test our faith" and whatnot; God is the ultimate trump card.
But this guy who claims that God exists writes a book making other random claims, and many of those claims were true.
... So? To take the Bible as an example, things which are reasonable in the Bible can easily be reasonable for non-divinely-inspired reasons. As an atheist, there are a lot of things in the Bible that I think make sense, but does that mean I have to believe in God? Of course not, nor would that be the reasonable reaction, because the things in the Bible I agree with have nothing to do with God. The veracity of one claim doesn't necessarily affect the veracity of another.
This person who thought up my religion was obviously a very intelligent person to have thought up a claim that can't be disproved, so I'm following him, whether or not he's right.
This is the naive part, above all else. It
is not hard to come up with a claim that can't be disproven, and such claims compose the majority of philosophical hoaxes and hogwash. One of the easiest ways to engage in pseudoscience, for instance, is to come up with claims that you know can't be easily tested, or tested at all, or disproven.
I don't say atheism is false, but it seems as sort of a lazy path to take. You learn more from trying to discover say, aliens, than trying to sit around arguing that aliens don't exist before even looking for them. But unlike the search for aliens, searching for God(s) costs nothing but time and thought.
You could say the same about anything. Do you call yourself lazy for not attempting to find every single other one of the infinite number of hypothetical entities out there? Do you also think I'm lazy for not trying to find fairies, unicorns, devils, flying purple people-eaters, hippogryphs, casinos on the Sun, planets made entirely out of beeswax, an immortality serum made from the tears and sweat of Thor, or a pill that makes you vomit confetti? Of course not, because there are an
infinite number of arbitrary and baseless claims that one could make about the world, and the fact that they are so arbitrary is why you don't bother searching for them to begin with; without any form of evidence or at least an
inkling that there might be a basis in reason, there's no reason to focus on one more than any of the others, and as I said, they are infinite in number. And no, my time and thought are not infinite resources, so I don't have time to look into every single probably-unprovable, mostly-mutually-exclusive, totally-arbitrary claim I can think of or that I read about, nor would it make much sense to do it.
So yeah, you might as well say I'm lazy because I don't believe in spectral werewolves who fight crime on Jupiter.
Actually, now that I think of it, I should take a proper scientific approach to this.
If you want to take a "proper scientific approach" to anything in life at all, you need to learn the value of testability, falsifiability, and the scientific method first.