Every time we worry about whether the American people will have the heart and will to see this worldwide struggle against terror through, we realize that we needn’t worry. Because we will soon enough be reminded of the nature of the threat against us, and of the character of our enemy in this struggle — whether in Iraq or Afghanistan, at home or around the world. It happened again yesterday: another bloody beheading for the edification of Web watchers everywhere. This — and worse — will continue to happen until these people are utterly defeated. Until they are, they will...