Recently Sohrab Ahmari, op-ed editor of The New York Post, saw something online that left him shaken. “This is demonic,” he tweeted. “To hell with liberal order.” His moral indignation led him to write a much discussed essay in the religious journal First Things. Castigating conservatives who see a possibility of coexistence with the left, he called for a religious Reconquista of American politics. The right, he argued, should “fight the culture war with the aim of defeating the enemy and enjoying the spoils in the form of a public square reordered to the common good and ultimately the Highest...