Have you tried William James's "The Varieties of Religious Experience"?
(I haven't myself, but I've heard that such a thing exists :)
There's actually a grad student here who wants to seriously study
religious epistemology (the nature of religious knowledge, how [or if] it
differs from ordinary knowledge, etc.), but he's a rarity. This stuff
definitely isn't "hip" in most philosophy departments anymore, and has
mostly been offloaded to departments of theology or religious studies or
whatever. But I know some people still write on the topic (e.g., Alston,
over at Syracuse -- again, I don't know what he actually says), and if you
work backwards a little bit, you'll find a lot more of them.
-- Evan Kirchhoff, kirchh@umich.edu