Populist patriots reject the elites of both parties. They believe President Trump defends their cultural beliefs from the left and their economic interests from the right. They see open borders, illegal immigration and multiculturalism threatening to redefine what it means to be an American, while unfair trade and a rigged tax code endanger their jobs.

The rejection runs both ways. Elite liberals too often talk about patriotism as if it’s a set of blinders preventing Americans from recognizing their country’s flaws. Likewise,...