It was never really a shift for me though. I was raised
  Methodist, which had an easy God concept. More metaphorical than
  anything else. They were focusing on being good and doing good
  things here on earth because it's good. Experimented with
  different religions, all around the Christian realm, Vipassana
  Meditation, some Osho later on. In the middle for about 5 years,
  I was Eastern Orthodox Christian. Full force into it. Was in a
  monastery for a short time. Even there, when puzzling the Triune
  concept and having it "click in" during prayer, it was
  comprehending a system to me, same as when quantum mechanics
  processes 'clicked in' as a teenager when studying black holes
  and QM for a high school paper. [I was going to be a theoretical
  physicist - kinda glad I didn't 'cause this was 1990, and I
  would've been stuck doing 'string theory' for years]. Anyway,
  did I *ever* 'believe'? Not in the way that people think of
  belief. I never knew what "faith" meant. Still don't. It's kind
  of a meaningless word to me. Always was. It was always
  psychological to me. I could see pragmatic benefits to prayer
  and the like. I experienced them. I'm agnostic because I see God
  as metaphorical for unknown processes and systems. The source of
  intention is cognitive and I don't believe in the Platonic realm
  (never did) - so there's no place I can say that a platonic God
  *could* exist: YET at the same time, there's more than I don't
  know about the Universe than I do, so I can't also say there
  might not be some sort of animating 'something' that operates on
  the level of valances and such. For all I know, some of what QM
  is describing *is* God. I don't know. And that's the thing: I
  don't know. So I leave it open.