I'm not exactly the best person to answer - I am an atheist, but I weirdly identify partially as a neopagan as well. Mainly, because I am very spiritual, though I do not believe in physical gods (or supernatural). I consider myself two things: one, animistic, in a spiritual sense - there's a spirit in everything in the universe, we're all made from the same stardust. Second, pantheistic - I find the earth-centric elements of most neopagan paths to be refreshing and beautiful, and am drawn to the celebration of the earth. I don't "worship" anything, though, just feel the sort of awe and beauty that comes with furthering my understanding of the universe.
I used to identify more as a neopagan than an atheist, though I never physically believed in gods, I was into the idea that gods are man-made ideas that can give us spiritual strength. To some extent, I think that's true no matter the religion, it just isn't as important to me now. I read a lot of literature - I think the best book I read about neopaganism was "The Philosophy of Wicca" by Amber Laine Fisher. Her book is a bit more "liberal" and less literal, than many Wiccan groups, but it's beautifully written. I think I was first drawn to neopaganism because I was always interested in mythology and stumbled across a neopagan book by accident when I was looking for mythology. I found it really fascinating that people would take old concepts and revitalize them with modern philosophy.
I do know several more serious pagans, and I find they tend to have three things in common: earth-centric (pantheistic) spirituality, fascination with the ancient world and its gods (even if it's a more romantic view rather than historically accurate), and an imagination for magic (which they might or might not physically believe in).
Hope this helps.