I respect all those values. And I guess there's a difference between having epistemological warrant for acting in a certain way, and using common sense to make your decisions. So it's possible to have values and beliefs, even if you can't fully justify them philosophically.

But having any values at all is still a result of implicitly trusting the intelligibility of the universe, which you don't necessarily affirm. If the universe isn't intelligible, none of your values really matter ultimately — but of course, you wouldn't be able to know. Maybe we're all crazy.

The reason I'm a Christian is because that problem bothers me. The universe seems intelligible; nothing would matter if it wasn't; therefore the only constructive belief possible is that it is intelligible. There are other rational beliefs, but they all boil down to theoretical, if not practical, nihilism.

So maybe I'm delusional, but there are other reasons to believe things than reason on its own. I am a fan of teleological arguments: "what is it for?" We need at least the illusion of purpose in order to function as moral agents. I prefer to believe that the purpose I have found for my life is also rational. If I'm wrong, nothing is lost because I live in an irrational, hostile universe. But if I'm right, I have the hope of being restored to the state of goodness I believe man was created in.

The assumed intelligibility of reality for me is evidence of God on its own. God is impossible to really define (as Mike said), but the Christian view is that he is the source of everything good — including order and intelligibility. The fact that order, or even the concept of order, even exists, is evidence of transcendent order. And once you're there, you're not far at all from a personal God.