One of my best friends is an atheist Unitarian Universalist, but the church he attended seemed to be more of a vaguely supernaturalist "unknowable mysteries" sort. Not explicitly theist, but also not the sort of place to properly celebrate the merely real.

For more information on the brain state stuff, you might want to check out Why God Won't Go Away: Brain Science and the Biology of Belief by Andrew Newberg, Eugene D'Aquilli, and Vince Rause. It had a pretty big effect on my understanding of religion back when I read it.