Last (probably) on this. A better rejoinder to the ISIS article is here (also from The Atlantic).
The author makes a helpful (if not terribly surprising) clarification:
The first thing I teach my undergraduates is that the English word “Islam” has two distinct but related meanings: the “Islam” that corresponds to Christendom (the civilization) and the “Islam” that corresponds to Christianity (the religion). The result is that the term “Islamic” has two separate but related uses, as does “un-Islamic.”
In his article and elsewhere, Wood has challenged the claim by Muslims that ISIS is un-Islamic by pointing out that ISIS members are self-identified Muslims. But Muslims who say “ISIS is un-Islamic” are not saying that ISIS fighters are not Muslims at all. They are calling ISIS “un-Islamic” the way a politician might call bigotry “un-American.”
Interestingly, he ends up at about the same place that I asserted in my last post that I believe the original author was headed, the “orrery of errors”:
All of this puts Muslims in a double bind: If they just go about their lives, they stand condemned by those who demand that Muslims “speak out.” But if they do speak out, they can expect to be told that short of declaring their sacred texts invalid, they are fooling themselves or deceiving the rest of us. Muslims are presented with a brutal logic in which the only way to truly disassociate from ISIS and escape suspicion is to renounce Islam altogether.