I think the new religions are gyms, fitness classes, sports, volunteering, book clubs, etc. My wife made friends at such places.
But it also depends on a person. I have never made a real friend at a gym or fitness class. I haven't done anything else like join sports team or book club. I also used to go to religious building (mosque) but never made new friends there. So don't think you really need religion for community building.
All those examples you mentioned while you may find some good friends, they cannot entirely replace the purpose of a religious community. Religion and spirituality are far more than a social club or hobbyist group. Maybe you did not make friends at a mosque for some ever reason, but it is more than just a place for friendship. Religious buildings serve communities, promote unity, educate children, and it is all based on belief and practicing these beliefs. True brotherhood in faith far outweighs most any other type of relationship between people.
But it also depends on a person. I have never made a real friend at a gym or fitness class. I haven't done anything else like join sports team or book club. I also used to go to religious building (mosque) but never made new friends there. So don't think you really need religion for community building.