Mary Douglas, a noted anthropologist, wrote a very provocative book in 1966 entitled, Purity and Danger. In this book she explains the origin of a need for purity in primitive tribes and the perceived “danger” of impurity. (And though I hear described this as a “perceived” danger, that is not to dismiss the very real danger of impurity run amok. Boundaries are necessary.)
I was raised in a sectarian, fundamentalist church which also emphasized purity and did so to excess. It emphasized rules and regulations to a fault, believing that the essential dimension of Christian piety was combating the forces of darkness, inside and outside. And to those who failed to live up to those standards there was always a hefty dollop of shame and guilt that was heaped upon them. In retrospect, I now see that shame and guilt was the essence of their belief system.
We have modern-day examples of purity run amok. The best one is the Taliban. It was interesting, though horrifying, to watch them rise to power as they emphasized purity morally, politically, and socially. But purity when it is running amok always runs out of grist for its mill when its primary focus is within its own ranks. At some point the machinery of purity has done all it can do within its own ranks and has to turn its focus outside, seeking to purify the world. Unfortunately for groups like this, the outside world always has a mind of its own and fights back.
Now there is nothing wrong with purity. It is an essential dimension of human experience. But mature purity will recognize that the impurity that it resists cannot be obliterated and that the very effort to obliterate it will result in a catastrophe if balance is not found. As Jung noted, “What we resists, persists.” The goal is to acknowledge the presence of impurity in our hearts and actions but to consciously pursue the pure instead. And I think that the Christian obligation to “confess ours sins, one to another” (James 5:16) is a ritual that facilitates this recognition of impurity and provides an opportunity for catharsis.