existentialism vs.rationalism: perspective on an old debate on religious truth

Yesterday's post opened a pandora's box of interesting discussion regarding truth and ikkarei emunah, and the volume of comments leads me to wonder if some of you sleep with a keyboard by your pillow : ) I just wanted to step back a little and offer some perspective. We can type from today to tomorrow, but this whole issue ultimately comes back to some old philosophical debates that I doubt we are going to resolve anytime soon.
In this corner: Existentialism. To quote Wikipedia (not the best source, but short and too the point): "Kierkegaard argued that "truth is subjectivity", meaning that what is most important to an existing being are questions dealing with an individual's inner relationship to existence. Objective truths (e.g. mathematical truths) are important, but detached or observational modes of thought can never truly comprehend human experience." How does one know the truth? How did Avraham Avinu know that it was G-d telling him to sacrifice his son and not some imaginary voice? Shouldn't he have rejected that voice considering that it contradicted both his rational sense of ethics and his prior promise from G-d himself? You can read Kierkegaard's “Faith and Trembling”, but for now, a short summary from the Stamford Encyclopedia of Philosophy - "His sole justification is what Kierkegaard calls the passion of faith. Such faith is, rationally speaking, absurd, a "leap," so if there is to be any talk of truth here it is a standard that measures not the content of Abraham's act, but the way in which he accomplishes it... To say that subjectivity is the truth is to highlight a way of being, then, and not a mode of knowing; truth measures the attitude ("passion") with which I appropriate, or make my own, an "objective uncertainty" (the voice of God) in a "process of highest inwardness."
In the other corner: Rationalism. The rationalists (and empiricists) argue that this makes no sense. Just because I believe it, how does that make it so? This is akin to arguing the “correspondance theory of truth” – things are true only because we can determine that they correspond to something “out there” and not our imagination. If I imagine and passionately believe in little green folk, does that make them real?
One of the answers to this is that there is a difference between the private subjective truth and truth which has a correlation in the human condition. If you speak to anyone about the little green men out there, they will likely have no way of relating to that experience. If you speak to someone about your relationship to G-d, even if that person is an atheist, they do comprehend your meaning. Of course, this argument has a refutation as well, and further defenses – ad infinitum. Most of the arguments back and forth have been made by rabim u'gedolim in philosophy already, though I doubt most academics approach their field with as much fervor as the debators in the jblosphere.
So much for philosophy 101. Historically, sifrei machshava have long since abandoned the metaphysical fight of the middle ages – the concern is not with proving the truth of Judaism in relation to what is “out there” in reality, but in discovering meaning in the experience of faith. The Piecezna quotes the Koshnizer Maggid that the tisch of shalosh seudos is mamash like tzadikim yoshvim in gan eden v’atroseihem b’rosheihem – and many people experience it as such. But if you sit there staring at the walls and just see men in furry hats singing songs and eating, while you wait for “proof” that this is gan eden, I guess you have a different perspective. The question is which one makes for a more meaningful existence?