Mock dialogue of the Theist/Atheist discussion here.

[Jenny A]

True, but the more nuanced phrasing won't help you prove god:  you can't prove anything about reality with pure reason.  To prove anything about reality you must have data. Pure logical systems such as math and formal logic do not expand our knowledge of what is in the real world, though they are of great use in analyzing facts in the real world.

I'm sorry, by reality, you mean God particularly? I think Aristotle did through pure reason. Refuting what is proven by reason by saying you can't prove anything about reality by pure reason is rather circular is it not? Reason is part of reality unless you are not real.

No, reason is not reality anymore than a dream or a novel is reality. You can for example prove various things about the nature of triangles as mathematicaly defined with math. But you can't prove the existence of a single triangle with math. Defining triangles does not cause them to exist anywhere but in our thoughts. As a thought, god exists. But unlike triangles he can't be found in the real world, but even then, I'm merely applying the label triangle to things already in the real world.. I could define a biangle as an object bounded by two straight lines. As a thought the biangle now exists. But I've got a long way to go if I intend to prove that one exists in the real world.