Hassan Hassan, one of the best analyst of the Syrian and Iraqi scenes, writing on ISIS’ doctrine of savagery for The Guardian:
Savagery is at the core of Isis ideology. But it is crucial not to play down that brutal acts have to be justified through sharia texts. Islamic fundamentalism is Isis’s ideology, so to speak, and every act has to be grounded in religious traditions. Muslim clerics who issue a “letter to al-Baghdadi” or a lengthy fatwa to delegitimise Isis miss the mark unless they understand the invigorating nature of this violent ideology. While Isis uses manuals such as Naji’s book, it references religious texts and stories. Muslim clerics should recognise that theoretical fatwas cannot sufficiently counter what I call “kinetic” sharia, consisting of stories and actions carried out by authoritative Muslim figures in early Islam, on which Isis relies heavily to justify its ideology. Statements such as “this hadith is weak” or “it is not permissible to kill prisoners of war” can be backed by religious texts, but how early Muslim leaders acted is similarly powerful, if not more persuasive.
The dilemma is that mainstream clerics sometimes steer clear of engaging in such stories because that has cross-sectarian implications. For example, critiquing immolation, killing captives and throwing people off high buildings risks arguing against Islamic figures at the core of the Sunni-Shia divide. Isis members claim these three acts were either carried out, or approved, by the first Muslim caliph, Abu Bakr, whom Shia consider an illegitimate leader – although many Sunni clerics dispute the references to immolation. Ahmed al-Tayeb, the sheikh of al-Azhar, the centre of Sunni learning, issued a generic statement addressing Islamic teachings about the treatment of captives and then called for “crucifying and chopping the hands and feet” of Isis members.