“To be sure, many of the Islamic State’s foot soldiers are ignorant of their own scriptures. Islamic scripture is vast, encompassing not only the Qur’an but also the ahadith, the words and deeds attributed to Muhammad by his followers. Collections of ahadith run into the hundreds of volumes, and that’s just the Sunni variety. The Shi’a have their own collections, adding more volumes to the pile. Want to find passages justifying peace and concord? They’re in there. Want to find passages justifying violence? They’re in there too. Medieval Muslim scholars spent their whole careers trying to reconcile the contradictions between them. It’s extremely difficult to do, which is why early Muslims called the effort ijtihad, or “hard work.” People chuckled at the news of two men buying a copy of Islam for Dummies on their way to join the Islamic State.14 But having spent two decades studying the intricacies of Islamic scripture, I empathized with their bewilderment.”
―
William McCants,
The ISIS Apocalypse: The History, Strategy, and Doomsday Vision of the Islamic State