First, I would say, is ideology. I have never spoken to any member of these groups, not just ISIS, but also Al Qaeda, Shabab, etc., who wasn't driven by the ideology. Beyond that, a lot of people are wounded in some way - they've fallen out of society in some manner. All of the ones I've spoken to seem to have veered off course from lives we consider acceptable and successful. Of course, there are others like Osama bin Laden, who was a wealthy and successful businessperson.

We know that Muhammad waged war against the Qurayshi tribe, his own tribe, and it's from that conflict that much of the concept of jihad and verses that ISIS now uses to justify beheadings come from. A young man just told me that he went back and read this carefully [and saw] the prophet and his people were fighting the Quraysh because they were not allowing the prophet and his people to practice their religion.

The systemic failure in the media in covering ISIS is that the majority of reporters are doing it in a semaphore fashion.

People who have left the group talk about how a religious inspiration took them to ISIS. It was their feeling of being marginalized as Muslims in the society where they were living, and then buying into the promise of a caliphate and of a Muslim land that is governed as in the time of the prophet. I have yet to meet anybody, or speak to anybody, who was not religiously motivated at some level.

It seems to me that a 9/11-style attack is impractical.

If we cover a court case involving a murderer, we would still seek out the side of that murderer, even as we realize that what people say is going to be self-serving.

It's become extremely difficult to speak to active ISIS members now. I was speaking to them in 2015, and the last one was killed in a drone strike.