I would contest that any communal group that meets face to face regularly develops similar bonds and that this is not exclusive of spiritual gatherings.
I think over the past few generations we have lost more of those reasons to get together, and church is one of the last hanger-ons of these close knit communities.
Agreed, but spiritual gatherings are often centered around questions or issues that are important, fundamental, and/or relevant to daily life.
That's something you generally don't have as much with other types of communal activities, and it's something that, in my experience, creates tight communities much faster, and bonds that often go deeper.
It's like friendships. There's a gradual strengthening over time, but usually the big 'jumps' are caused by personal or interpersonal crises; moment of vulnerability.
I think over the past few generations we have lost more of those reasons to get together, and church is one of the last hanger-ons of these close knit communities.