ON SATURDAY, I SPENT a couple of hours chatting with a friend who runs an evangelical bookstore. He set the shop up in the heart of Mormon country and has kept at it for 30 years. "I have to say, I admire your devotion," I tell him. "I never take credit for personal virtue," he says. "That's you guys." It's the way things are between us. We don't play a lot of slap and tickle. We know where we stand. Evangelical faith comes out as confidence and boldness, which Mormons often see as brazen. Mormon faith comes out as obedience,...