A nameless woman “dumped on a street, arms and legs cut off, entrails eviscerated” — this is just one testament from Bing West’s account of Fallujah in 2004. This was the first mini-caliphate of Al Qaeda in Iraq (AQI). West’s quote still matters, because it sums up the real-world impact of Salafi jihadism, the ideology of sick totalitarianism that once inspired Abu Musab al-Zarqawi and that now motivates Abu Bakr al-Baghdadi. Leading ISIS, Baghdadi is painting Iraq and Syria with the blood of all those who do not yield. And be under no illusions: ISIS does not believe in geographic...