I have spent some time pondering the different Christian groups, our similarities and our differences. We have a large common ground, and then we have our distinctive doctrines. These are often doctrines about which our group has thought long and hard, areas in which we take a unique pride as our special identifying mark.
I have noticed that each group's most distinctive doctrine -- the one which they hold but almost nobody else does -- is very likely to be a matter of pride with them. It is their marker, like a mockingbird's white stripe, a quick way in which each group can recognize its own as quick as a flash. Most groups are both vocal and defensive about their markers. Most groups have devoted a large portion of their theological thought to the area in which their own group is unique, to establishing and defending their claim to correctness. Each group typically considers that marker to be the sign of the most true, most devoted, most pure religion.
I have also noticed that, for most groups, it also happens to be the area where they are most likely to be mistaken, most likely to be mistaken badly, and least likely to be receptive to the thought that it is their weakest and most mistaken point, not their best and most valuable contribution.
I'm not going to pick on anyone else's group, tempting though it may be. I'll mention my own. In our particular group, there is a lot of emphasis on the doctrine of "fellowship". And of course all Christians have some basic familiarity with fellowship: it is the family-like bonding and common purpose which unites all Christians to each other through Christ. It is grounded in the shared hope given us by his resurrection, and by the promise that he will return. It is distinguished by brotherly love, by gentleness and respect. But our group, having made "fellowship" a distinctive marker, discuss it almost exclusively in terms of exclusion and excommunication. As we focus so much on "fellowship", we do not discuss how to build the brotherly love or encourage each other; we focus on how to make sure we don't have fellowship with anyone we shouldn't. And so our most distinctive doctrine, the area in which we pride ourselves, the area where our resources focus, has become the area in which we are most likely to forget the most important things that God wants us to learn about that very topic.