No dogma, no religion, even with the most religious. Pick up a '12&12' some day, and read it, carefully.
http://www.amazon.com/Twelve-Steps-Traditions-Alcoholics/dp/0916856011
Also, "Alcoholics Anonymous Comes of Age" might be useful
http://www.amazon.com/Alcoholics-Comes-Age-Brief-History/dp/091685602X
The 'Big Book/Blue Book' ('Alcoholics Anonymous') helped me, but the '12&12' and 'Comes of Age' were the hooks that kept me, lead me to discover the only group on the planet that, as a group, wasn't out for something. The closest thing to altruism that exists in our known universe. No bosses, no hidden agendas, no treasury to speak of, just a responsibility to pass on what was given.
You could try "The Twelve Steps and Twelve Traditions" and "Living Sober" - they both helped me a lot and were written 15 and 30 years after the "Big Book" Alcoholics Anonymous.
But the one book (that is not published by AA) which told me the most about AA and really helped me come to terms with practicing the 12 Steps as an Atheist is the book "Not God" by Ernie Kurtz