In August, a guest on Tucker Carlson’s podcast said something that immediately caught his interest. The United States faces a fundamental rift “between heritage Americans and the new political class,” Auron MacIntyre, a columnist for Blaze Media, argued. “Heritage Americans—what are those?” Carlson asked. “You could find their last names in the Civil War registry,” MacIntyre explained. This ancestry matters, he said, because America is not “a collection of abstract things agreed to in some social contract.” It is a specific set of people who embody an “Anglo-Protestant spirit” and “have a tie to history and to the land.” MacIntyre...