As far as the Islamic State itself is concerned, there is no question that it is Islamic--in fact, it holds that any Muslims who doesn't get on board with the State's claim to represent Islam is placing himself outside the fold of true Islam. (Chapter 8, pp. 221-2.)In other words ISIL is "loading the term." ISIL is redefining terms and phrases commonly used among Muslims to prop up their power, authority and self serving ideology.
So in ISIL's cult jargon a Muslim who not just anyone who happens to be a Muslim but instead one who serves Abu Bakr al Baghdadi's gang of murderers, thieves and power hungry usurpers.
Let us be careful about how we discuss the criminal network that is ISIL lest we should somehow play into their hands.
It should be noted that Robert Spencer is part of group of organizations and individuals that some have called the Islamophobia Network.
The book contains endorsements from other individuals who have long been linked to what some have called the Islamophobia Network, namely Steven Emerson, Pamela Geller and Geert Wilders.
Why send even more money to the Islamophobia Network?
I would recommend Islamic State: Rewriting History by Michael Griffin for those wanting a resource to learn about those genocidal, criminal murderers in a responsible manner.