The closest thing to a secular church that I have ever encountered are Light Opera Societies. In the UK lots of towns above a certain (quite small) size have one.

They pursue harmless but uplifting goals. The goals are challenging, but achievable. Participants must follow the instructions of a group leader precisely. Participants must learn to trust other group members. Performing in front of others is a fairly intense social experience. Once you have signed up, attendance every week is almost mandatory for a significant period of time.

EDIT: for those not into this kind of thing, Light Opera means Gilbert and Sullivan, or Singing in the Rain.