I'll be the first to admit that I've heard a lot of irrational arguments from people trying to advocate or disprove a particular religion. But you're saying that because you've only heard or explored irrational arguments for theism or atheism that all arguments for theism or atheism are irrational. Your argument is irrational.
That's not what I'm saying at all. Don't mistake me for an atheist.
I'm saying that without the ability to even vaguely define what a "God" is the question "does God exist?" is a non-question.
Sure you can define God as the 'metaphysically ultimate being' but that's a cop-out definition that means nothing. 'Ultimate' just means there isn't another one after that... ranked assumedly by some magical badassery rating.
I might as well ask you "is there a Fnooob?" on the basis that Fnooob is the metaphysically penultimate being. You have no basis on which to answer the question because the question is nonsense.
We're all familiar with stories about various gods because we've been fed them since childhood, and that familiarity makes us think we know what they are, but we really don't.
Sorry, maybe I wasn't clear enough. Questioning the existence and using rational arguments for or against the possibility of free will itself is a rational argument that affects theism or atheism. My point wasn't to tell you what my friends believe but to help you understand that there is a whole body of work dedicated to substance dualism that is based in rational arguments. That's just one philosophical subject, there are plenty others. Simply waving your hand and saying that rational arguments about theism or atheism are absurd is lazy at best. Take a look, there are plenty to be had.