In a Sunday lecture a few years back, our fairly-orthodox rector said something like, the church has to believe certain things. It can't be just a group of people who get together to worship on Sundays and try to do good works — if that were all it took, he said, "then the church would be just a religious fraternity." (I didn't think to write down the rector's exact words, so I'm having to reconstruct them as best I can.)
At the time, I wondered: What's wrong with being "just" a religious fraternity? For some reason, the question came to mind again this morning at church, as I was lying on a blood-drive bed with a needle in my vein.
As a thought experiment, let's define that term — "just a religious fraternity" — as a group of people that sees the following as the essence of their collective mission and group identity:
to try to help each other successfully get through life;
to try to help non-members improve their own lot, including by offering membership in the group; and
to regularly glorify "God" together.
Sure, the devil is in the details. But I can't think of anything else that I'd need a church to be. I'd like for the church to use the Bible and familiar prayers and hymns; to baptize people; to hold communion services; etc. But those seem more a personal preference for the familiar, as opposed to essentials of the group's identity.
Putting it another way, drawn from a friend's recent experience: Suppose I'm on a long-term assignment in a very poor country where there are no churches, because another religion is dominant. A local Rotary Club tries to do things to improve conditions for the population. Unlike Rotary Clubs elsewhere (or so I understand), this local club holds generic, lowest-common-denominator worship services every week. I can readily imagine that the club's spiritual life could be at least as fulfilling as that of my home parish.