Everything done by ISIS has some type of Koranic reference. In this case, consider the words of Sur An-Nisa’:
(4:88) What has happened to you that you have two minds about the hypocrites even though Allah has reverted them, owing to the sins that they earned? Do you want to lead those to the right way whom Allah let go astray? And he whom Allah lets go astray, for him you can never find a way.
(4:89) They wish that you should disbelieve just as they disbelieved so that you may all be alike. Do not, therefore, take from them allies until they emigrate in the way of Allah, but if they turn their backs (on emigration), seize them and slay them wherever you come upon them.** Take none of them for your ally or helper**,
Read very carefully this Grand Mufti’s condemnation and you will find it completely devoid of any condemnation for their slaying of religious minorities (including Christians). You will find that he condemns them for slaying Muslims that are not sufficiently radical.
From Al Monitor, June 30:
Saudi Arabia threatened by ISIS advance in Iraq
Contrary to an emerging consensus in the West and the Middle East, the turmoil in Iraq does not benefit Saudi Arabia, nor is it a “dream” for Saudi King Abdullah bin Abdulaziz. While relations between the Saudi royals and Iraqi Prime Minister Nouri al-Maliki are among the most strained in the region, it is one thing for the Saudis to view Maliki as a divisive figure beholden to Iran, and something patently different for them to be actively supporting the armed Sunni rebellion, which al-Qaeda offshoot the Islamic State of Iraq and al-Sham (ISIS) is spearheading.
The prospect of a failed state torn apart by a sectarian civil war along its border, another one in Syria and an al-Qaeda “state” rising up from the ashes of these two civil wars must be a disconcerting one for Saudi Arabia. While both Iraq and Syria have publicly blamed the carnage in their countries on the Saudis for what they maintain is Saudi support of “terrorists,” including ISIS, the al-Qaeda affiliate itself has vowed to “conquer” Saudi Arabia after it has “vanquished” the regimes in Damascus and Baghdad. More than any of its neighbors, Saudi Arabia has the most to lose from the conflict in Iraq spiraling out of control.
This Grand Mufti is scared. He is scared that he will be viewed as a hypocrite and will be put to the sword, per Koran 4:89.
It’s that simple.