Whenever theists present me with the argument of not being able to substantiate the non existence (or existence) of god, I tell them, they are absolutely right. There is no way I can prove 100% that god is not real. That's not even my position. Luckily, however that doesn't matter much. My position is this. God cannot be proven false, as a concept, no. However the major monotheistic religions (the Abrahamic ones) have an embarrassing amount of holes in them. Mathematically, historically, logically, geographically and MORALLY, the books are full of inaccuracies. All claiming explicitly or STRONGLY implying infallibility. As such, showing that these texts have (many) faults in them, you can debunk that specific religion or specific representation of god's nature as untrue. Now, assuming one doesn't go into denial (is often the case), all three major monotheistic religions are known to be false. Now we are left with two things. All of the other world religions, which most of us do not accept, and a deistic version of god. So we're left with deism. And that means a god may exist somewhere but it is an entity that would never directly interfere with humans and has nothing to do with our ongoing existence. Once you're left with a vague definition of a god that has no anthropomorphic properties at all, for me we're left with one conclusion. God isn't worth believing in. Provided that, deism is the only theistic worldview that's even remotely logical, I can say with confidence that believing in that version of god is a waste of time.