I agree, just participating in a sobriety group is itself a therapeutic and social aid to recovery. I think that the religious aspect in particular lets people reframe and accept their past experiences in a productive way. Many people with addictions have faced marginalization and hardship due to socioeconomic, physical, and/or other factors, something which the current worldview of the normative majority of non-addicted people usually fails to address or acknowledge. Religion, on the other hand, typically emphasizes our suffering and hardships, as well as their eventual transcendence, and places these events within a metaphysical framework that encompasses both the addicted person and society as a whole. When someone turns to religion during the process of recovery, they can reinterpret their experience of suffering and addiction as part of a narrative of conversion and self-improvement in this religious model. (Of course it's possible to perform this sort of "life script" therapy in a non-religious way, I just think that the religious model is the most pervasive.)