http://www.merriam-webster.com/dictionary/religion

Definitions 2 and 4 can, I think, be applied to some extent to the “12-Step Program”, although definition 2 is oddly circular, if you go by Mirriam-Webster’s definitions. It fits, at least, the semantic definition of “religion”. You and Marina both seem to assume that “religion” means something along the lines of the template laid down by the Judaic/Christian/Islamic faiths. Although those are all religions, they aren’t the be-all and end-all. Shinto and Buddhism in Japan, for instance, are both considered religions, but are “practiced” in a way very different from that of most western religions. Just because your belief structure doesn’t mimic the Judeo-Christian one doesn’t mean you aren’t a religion. In a way, the fact that your organization is based on belief is what makes your a religion.

Mirriam-Webster defines “religious” as “relating to or manifesting faithful devotion to an acknowledged ultimate reality or deity” and I have difficulty seeing how that doesn’t apply to an organization which encourages belief in a power greater than one’s self by suggesting that this greater power can improve one’s life. That you choose not to “kick people out” who don’t choose to believe only reflects on how strict you are, not the nature of your organization.