Mock dialogue of the Theist/Atheist discussion here.

[Jenny A]

Well, we could also use the scientific method and evidence to prove that. Lots of things demonstrate that reason alone isn't sufficient to prove objective existence.

Yes you can't know everything through pure reason. That is different then to say you can't know/prove anything with pure reason.

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. Ultimately, any proof concerning real things must be based upon real things.