...existential theology has done a good job of mapping the existential and experiential terrain of human experience as it relates to God. Again, existentialism points to our Augustinian restlessness. You can't live without God and not have that impact you in some existential way. We have a natural desire for a supernatural end, and that desire will always be left existentially unfulfilled until it finds rest in God. Existential theology does a great job at describing and evoking both this desire and its lack of fulfillment.
This is something I think I've not fully been able to articulte in the past, especially w/r/t my ongoing facscination with existentialism and in particularl Kierkegaard.
Ultimately, Kierkegaard's epistemological work enthralled me (and continues to) because I think he maps out a condition that still matters, even in 21st century modernity. Kierkegaard, I think, is a theologian first and foremost (earlier works notwithstanding). His main life's work was later in his writing, and being faithful under modern epistemological conditions was a constant source of tension for him, IMO. The "ache" or something similar to Charles Taylor's term regarding "fullness" in a secular age brings about the need for existential theology -- otherwise, we're perhaps speaking a disingenuous language.