Christianity is by far the largest religion in the United States; more than three-quarters of Americans identify as Christians. A little more than half of us identify as Protestants, about 23 percent as Catholic and about 2 percent as Mormon. But what about the rest of us? In the Western U.S., Buddhists represent the largest non-Christian religious bloc in most states. In 20 states, mostly in the Midwest and South, Islam is the largest non-Christian faith tradition. And in 15 states, mostly in the Northeast, Judaism has the most followers after Christianity. Hindus come in second place in Arizona and...