I agree with Mr. Nobody here. I reject the idea of "hierarchical spirituality". It's bad enough being a subject while I'm alive, I gotta be one for eternity? No thanks.
I think Mr. N makes a valid point that in this being the Quest for the Theory of Everything it would include the spiritual realm (if such a beast exists). For me though, I don't see a need or a reason to separate spiritual from physical. If there is such a thing as a spiritual experience then I think we're all having it right now.
I remember a good analogy I heard a few years ago: all the terminology we use, all the measurements we take, all of the things we do which require the use of language are simply ways that we "map" nature or our reality. The problem comes when people confuse the map with the territory; especially when the map is constantly changing and nobody can even agree which way is actually North.
Anyway, I view the concept of God as little more than a reflection of our history. There have always been rulers and there have always been the ruled. I guess it's difficult for some people to conceive of a spiritual existence without comparing it to the brutality of human affairs. I mean, the Kingdom of Heaven? Didn't we decide Kings were a bad way to run things a few hundred years ago? I see strong atheism and anarchism as almost inseparable in their theory but maybe that's just me.
Sorry for the rant, just my .367% of a cent.