You hint at the underlying cause, if only obliquely. I never understand why educated people like the author can't look past the religious issues and address the real issue: namely, absent a religion, the people who embrace the more violent aspects of Islam would have created some other justification for war and terror.
Let's examine this statement a little closer. What it says is that there a certain people(s) who (1) have a limited IQ [ie they lack the intellectual capacity to explore/invent and otherwise interest themselves], and (2) are very violent. They don't actually need a religious basis (ditto Genghis Kha, Attila, et al) to justify their deeds. All they need is something to harness and focus their rage.
One could go on and posit that the Jews are the exact opposite (high IQ and very passive) and that their religion reflects this orientation - scholarly and reflective. Christians are somwhere in the middle - driven by exploration/experimentation and manifest humanity, but not shy about territorial/cultural expansion.
In each case, the adaptive religions are fairly recent. Evolution has been going on for millenia - religions that are 5k, 2k and 1.5 year old are as current as last year's World Series in real terms.
The real issue is: how do civilized people deal with primitive savages, regardless of their 'cause', be they common criminals, fascists, communists and now Islamics?