AA has no doctrines, no creed, no statement of beliefs, so there’s not much to indoctrinate someone with in AA. It is God as we understood him and I have seen atheists, Buddhists, non-theists, Christians, and Islamic people effectively do the 12 steps to improve their lives.
Also, there are no membership dues or fees, the most we ask is for $2 to be put in the basket when the 7^th tradition is passed around and under $20 for the Big Book.