Charles Krauthammer caused grave unhappiness among some of his admirers last month when, speaking on Fox News, he attacked the Dutch politician Geert Wilders. At issue was Wilders’s campaign against the “Islamization” of Europe, particularly in the Netherlands. “What he says,” Dr. Krauthammer charged, “is extreme, radical, and wrong”: He basically is arguing that Islam is the same as Islamism. Islamism is an ideology of a small minority which holds that the essence of Islam is jihad, conquest, forcing people into accepting a certain very narrow interpretation [of Islam]. The untruth of that is obvious. If you look at the...