This weekend I talked with someone whom I think highly of who told me all of the different churches he has been a member of. At various times, depending on where he has lived, he has attended Presbyterian, Anglican, Bible, Evangelical Covenant, Campbellite, Christian Missionary Alliance, non-denominational, and house churches.
Whereas for me (even before I became a Lutheran), the criteria for which church I joined had to do with what it believed. For him–and I suspect there are a great many like him, possibly a majority of evangelicals–the criteria has to do with the people in the different congregations, the kind of “fellowship” they experience and whether they like the pastor. Theology is something held by the individual, with these different churches being more or less OK with whatever the individual member believes, within a few parameters, so that these churches today assert few theological distinctives for themselves.
According to the Lutheran mindset, the heart of a church body, the basis of fellowship, and the definition of unity must be its confession. Whereas for much of American Christianity, fellowship and unity are the heart of a church body, which allows for diverse confessions.