This makes sense -- I was trying to figure out why various secular groups with which I'm involved (e.g., improv theatre, or the guys at the gym) don't have any

This makes sense -- I was trying to figure out why various secular groups with which I'm involved (e.g., improv theatre, or the guys at the gym) don't have any of the church-like feel. I think it's because they're too flexible -- people are always leaving, forming sub-groups, etc. I like those people but they would never show up at my house to mow my lawn, as another commenter described. Or maybe 'flexibility' is the wrong word, since the groups I mention are activity-specific, and one's interest in the activity ebbs and flows, whereas one's interest in fellowship with other people in the quest for some kind of human-level goodwill would presumably be constant.