I've stated on here that I believe rationality ought to be part of politics. I go so far as to say that I am a sort of rationalist. I say "sort of" because "Reason", "rationality", and so on, don't mean the same thing to everyone. Not only do people disagree with the meaning and implications of rationalism, they also feel divided on the issue. My "sort of" is rhetorical: I mean to say "reserve your judgment for after you hear me out"
I believe that rationality can be summed up with a single, simple maxim: Find reasons for your beliefs which are logically consistent. When you can no longer do this, acknowledge this, but continue to reflect on this hinge proposition.
There are no appeals to a universal "making-sense-ness" within the heads of reasonable persons. There is no pointing at the unreasonable, or routing out the irrational, or exercise of epistemic chauvinism. That isn't to say that rationality can't or hasn't been used for these or other negative ends. It certainly can. However, rationality is, in the end, a loose position. It is this looseness that I wish to point out.
Suppose I claimed that I believed in God. If someone then asked why, I would say, "Because I experience his existence every day" If they retorted, "Why don't I experience this, if he is so wonderful?" I would reply, "I am ignorant. I wish he made this known to me, but I'm afraid that I can't say"
This is a rational position. It is a position I disagree with, but it is a rational position. It is epistemically rational. There is a difference between rationality and proof. Having reasons for your beliefs, finding warrant, and applying these constitently is all that is required to be rational. "Proof" is the deduction of a position from axioms. However, argument, and reasons for positions, are much more varied than deductive systems. One may only use deductive systems to justify their position, but it's not necessary for rationality.
I chose "God" because I'm mostly speaking to that group of persons who think that concluding that God does not exist is the only conclusion a rational person who is honest or not arguing for "Feel-good" constructs could come to. Rationality is not so restrictive that the atheist/agnostic/materialist/whatever world-view is a for-ordained conclusion. Beliefs as divergent as "There is no purpose in the world" or "There is a God" or "The World is nothing but Mind" can be justified underneath the rubric of rationality . We can rationally disagree and discover where, and possibly why, we diverge.
This doesn't reflect on the "truth" of either claim, or any claim within rationality. Rationality and "truth" are two separate issues: At base, if it were true that irrationality is "true", then rationality would be against "truth". All this is intended to do is point out that "rationality" really, really, really doesn't say that much, and that therefore theism, disagree with it or no, can be rational.