I'm not sure Alateen is the best choice. I think that someone might approach the mother and tell her that forcing her son to attend church could keep him from accepting the religious principles she wants him to adopt. The most important job of a teenager is to develop into an adult, and that involves gradually allowing them to make more and more of their own decisions. Have someone suggest to the mother that forcing religion on her son may have the opposite effect, and that she should think about what is best for him long term.
She had to make a decision about drinking on her own and he will need to do the same with religion.