‘The Bible Belt is collapsing,” says Russell Moore. Oddly, the incoming president of the Southern Baptist Convention’s Ethics and Religious Liberty Commission doesn’t seem upset. In a recent visit to The Wall Street Journal, Mr. Moore explains that he thinks the Bible Belt’s decline may be “bad for America, but it’s good for the church.”

Why? Because “we are no longer the moral majority. We are a prophetic minority.”

The phrase is arresting coming from such a prominent religious leader—akin to a general who says the Army has shrunk to the point it can no longer fight two wars. A youthful 41, Mr. Moore is among the leaders of a new generation who think that evangelicals need to recognize that their values no longer define mainstream American culture the way they did 50 or even 20 years ago.

On gay marriage, abortion, even on basic religious affiliation, the culture has moved away. So evangelicals need a new way of thinking—a new strategy, if you will—to attract and keep believers, as well as to influence American politics.