Living in Northern Ireland makes this especially interesting for me, being an atheist myself. It's one of the things that has put me off the idea of AA and support groups here (although I still go to AA when I can - the meeting is strong with some decent people, although I find forums easier to work with).
I have no problem with people having religious beliefs that coincide with their recovery, but it can go too far. For instance, I once had a counsellor who advised me to seek solace in the bible and that God had a plan. When I said that I was an atheist, she starting attempting to edge me towards religion! Scary stuff - it put me off therapy for a long time. With hindsight I should have gotten a referral, but it just shows how damaging the wrong approach can be with people, especially if they're on the precipice of wanting to get better which is usually the case.
I've always toyed with the idea of someone starting a group that had a strong secular message. It's obvious to me the AA approach doesn't work for everyone and no matter how much the idea is protested that there is a bias towards non-secular beliefs simply through the wording of the original twelve steps. This is NOT to say that AA doesn't do a lot of good for a lot of people. But a one-size fixes all organisation can only really do so much.