AA is "spiritual," not religious. In AA, a "spiritual experience" is defined as "a personality change sufficient to recover from alcoholism." I know many atheists and agnostics successfully (and happily) sober in AA. Some people think of their Higher Power as the spirit within themselves (not their conscious, selfish selves, but something deeper), some think of it as the Power of the Universe, some think of it as karma, some think of it as the power in the group of recovering/recovered alcoholics banded together with a common purpose.
Even though the Steps mention God, the Big Book is very specific that it is a Higher Power of your own understanding, however you conceive it. You will find religious people in AA, and most people believe in the power of prayer or meditation, but AA doesn't advocate any religious belief, church membership, etc.
HG is right, though--it is he who should be doing the research on his own recovery.
I'm sorry you are going through this upsetting experience (you may find yourself more upset as you think about it later). It does sound, though, from the way he told you without your interrogating him, that he was deeply shocked by his own behavior. Hopefully it shakes him up enough to get serious about recovery.