The AA treatment has a component that many atheists may interpret as religious or spiritual. If that's your interpretation, and you are actively hostile to that belief, then your own world view is not compatible with either the treatment path or the social group you will encounter. That is not going to be a high probability scenario for recovery, and it may interfere with others' recovery, and that's why you should find another group.
Which other group? That's a different question. There doesn't have to be an alternative for AA to be a bad option. Though as it turns out, there are many options. A little searching shows there are AA for athiest groups which, presumably, use a modified protocol.
Which other group? That's a different question. There doesn't have to be an alternative for AA to be a bad option. Though as it turns out, there are many options. A little searching shows there are AA for athiest groups which, presumably, use a modified protocol.