The debate over Islamic terrorism has shifted so far from reality that it has now become an argument between the administration, which insists that there is nothing Islamic about ISIS, and critics who contend that a minority of Islamic extremists are the ones causing all the problems. But what makes an Islamic radical, extremist? Where is the line between ordinary Muslim practice and its extremist dark side? It can’t be beheading people in public. Saudi Arabia just did that and was praised for its progressiveness by the UN Secretary General, had flags flown at half-staff in the honor of its...