In commemorating the 100th anniversary of the end of World War I, French President Emmanuel Macron said: “Nationalism is a betrayal of patriotism. By saying ‘Our interests first, who cares about the others,’ we erase what a nation holds dearest . . . its moral values.”

That might sound nice, but Mr. Macron got it almost exactly backward. It is through the nation that moral values can be upheld and sustained. In America, our ideals are deeply intertwined with our national traditions and institutions. Mr. Macron may have intended...