Mike Huckabee insists he spoke out of ignorance, not malice against the faith of a Republican rival, Mitt Romney, when he asked, “Don’t Mormons believe that Jesus and the devil are brothers?”

Although there may have been a kernel of truth in his question, Mr. Huckabee’s confessed ignorance about Mormonism is widely shared.

Americans are notoriously uninformed about faiths other than their own, and they are particularly perplexed about Mormon beliefs. Mormons make up 2 percent of the American population, and their faith, which emerged 177 years ago in upstate New York, is a relative newcomer.