Some differences—between snowflakes, for instance, or symphony instruments—make us delight in diversity. Other differences, however, like those between vinegar and baking soda, combine to set off a furious reaction.

I learned the volatile nature of diversity in a church during an all-committee night. I had been pastor of the church for about a year and a half. The congregation was growing in its understanding and practice of Christian discipleship, but the growth was not without discord.

One committee was discussing spiritual qualifications for leadership. A young man was telling his fellow committee members that our increasing emphasis on a personal relationship with Jesus Christ was making us too narrow and restrictive.

"Look," said Jim, "none of us is a saint. If you don't have room for people who doubt and struggle and don't speak perfect theology, I won't be part of it."

A long, strained dialogue began. Over an hour later, we realized Jim was hearing one message—not ...