Alright, so I know I've been mostly lurking around this site for a few months now, but I've been putting off typing all of this out because I knew it was going to take a good deal of time and would wind up being pretty long. But I finally bit the bullet and typed it all up for my INFP group's discussion board, so I'm just going to cross-post it from there...
Religiously speaking, I was raised primarily in the Episcopal church. When we were living in Michigan (ages 5-10 for me), however, my parents had a falling out with the local church and we just sort of stopped going for a while. After we moved to Missouri, we started going again to the local church there. I actually wound up being confirmed in that particular church (though, to be honest, that was mostly because the "Sunday School" class for my age group turned into "Confirmation Class" after we hit our teens).
As far back as I can remember, though, I never really had an intuitive sense of the presence of God or Jesus in my personal life. It just never really felt like more than mythology to me, though it was a while before I fully acknowledged it to myself. Really for most of my later years of attending that church I just went to sing bass in the choir and get away with legal underage drinking (I know it's just a sip a week, but hey... it was funny to me at the time).
I was also turned off emotionally by the character of God in the Bible, as some of you have also cited. I didn't understand how an omnipotent, omniscient, and wise-beyond-measure being could act so humanly, and oftentimes even act like a spoiled child throwing a tantrum. This lack of dignity in the deity was personally disturbing to me. Also, the hateful conduct of individual Christians who I encountered was very disturbing, and really made me question.
Eventually... somewhere around 16 or 17... I started really thinking rationally about these intuitive and emotional impressions I'd been getting for so many years. I started seeing Christianity and other religions as nothing more than mythology, and in fact (being fascinated by ancient history and mythology in general) started to be able to see a chain of progressively more sophisticated myths over the course of history. Basic animism and naturalistic spirit worship moves to polytheistic systems that give the nature spirits names and personalities, then as human understanding of the natural world grows, the necessity for large numbers of gods progressively dwindles, eventually shrinking to one (Zoroastrianism, Judaism, Christianity, Islam), and then finally none (Buddhism) but still retaining supernatural beliefs. While I acknowledged that the modern mythologies are more sophisticated than the more ancient ones, I began to see them as nothing more than mythology regardless.
I still had a bit of problem, however, reconciling this new view with the beauty, majesty, and greatness of religiously-inspired art, especially music (by which I mean classical and symphonic music, not this mass-produced Christian pop-rock that seems to be pervading the culture lately). I've always been a very aesthetic and musical person, and for a long time, and I kept having to ask myself if their beliefs were so false, how did they produce something so glorious from those beliefs? Eventually, from looking at the ideas of Humanism, I was able to re-frame this in my mind. It wasn't their beliefs that were the causative factor in creating such beautiful music. If that were the case, then secular-inspired music would be greatly inferior to the religious, which is obviously not the case. Instead, the music, regardless of its inspiration, was coming from within them and was a reflection of their humanity more than any deity's grandeur.
That severed my final real tie to Chistianity (tenuous as it was), and I considered myself a bit of a spiritual explorer for a while, trying out various ideas until finally settling into atheism, specifically Secular Humanism, philosophically speaking. I've also got some other less-standard beliefs that form part of my philosophy, but they do not venture into the realm of the supernatural, and are simply reflections of my personal perception of the world through my intuition and emotion.