Blogs are too brief to develop ideas fully, so this blog backs up to an earlier idea: The way that religion functions as a pattern for living. Patterns create clear boundaries, so that one can tell if you are in the pattern or outside it. The plain dress that my parents grew up with is an example of such boundaries. Women who wore the headcovering were inside the boundary and could be trusted to follow the pattern of simplicity and obedience that the boundary enclosed.
Now boundaries are good. Although bounded-set thinking has its problems, boundaries—and the pattern they enclose—are necessary to enable us to cope with life. If we had to work out from the beginning what to do in every situation what we should do, we would live paralyzed lives. We would be unable to act, because we would be constantly analyzing each action to decide whether it is right or wrong. Boundaries and patterns serve as a useful shortcut so that we can function according to a high moral and ethical standard.
But boundaries—and the patterns they enclose—fit only the situation in which they were created. A friend described to me the way that her Catholic community responded to her contact with non-Catholic friends. It reminded me of my own BIC background: We socialized with our own and avoided outsiders. That practice of separation (whether Catholic, with its understanding that it is the only true church, the mother church, or BIC, with our understanding that we had regained the purity of the first church) worked within the setting in which it was created. But in a new setting, North America as we know it today, it is simply out of place.
For many years missionaries from widely differing backgrounds have found themselves working as sisters and brothers when they go to countries with no significant Christian presence. Similarly, as Christian faith becomes a minority option in North America, Christians of various backgrounds do not have the luxury of separating from each other in the way that we once did. We belong together, and the old patterning (which promoted separation from other Christians) is actually destructive.
One can consider a variety of boundary issues (one thinks of the old saying, “Christian boys don’t smoke, drink, dance, or go to movies, and they don’t go with girls that do”) that have lost their relevance as the pattern they enclose has less and less to do with the world we live in today. So boundaries are good, but the centre of the Christian faith (which in the long run creates the boundaries) is essential.
I suspect that one primary source of reversions from Christianity (whether in the sense of moving from one church to another, or in the sense of leaving Christian faith) is the way that we have often substituted the pattern we know (complete with its boundaries) for the Christian faith in itself. That faith is primarily centred on a relationship with Jesus Christ, which is why Bruxy Cavey has emphasized the saying in his own ministry, “Christianity is not a religion; it’s a relationship.”
Hiebert, Paul G. Anthropological Reflections on Missiological Issues. Grand Rapids, MI: Baker, 1994.
 I am working on a paper on bounded-set thinking and centred-set thinking in which I develop these ideas more fully. The terms and their relationship to who belongs in the church were mediated to missiology through the work of Paul Hiebert (1994).
 This assertion can be debated. See the work of people like Reginald Bibby in Canada and Christian Smith in the USA for a good picture of religion in North America today.