This is a great phrase in a very interesting article.
The only point at which he falls down is assigning the 18th century as the moment at which Islam became violent and a threat. It was violent and a threat since the day of its founding, and is based on violence, and has always extended itself that way.
The 18th century was simply another flare-up, although it was, obviously, the first US contact with Islam, since we had just been founded. Remember, we were having to fight Islam in the Med within only a few years after our founding.
One of the problems is that while most Muslims do not agree with AQ and are not members of the Shadow Army, they are members of the Ghost Country (the umma, the house of Islam), and it is easy both to intimidate them and to radicalize them because the mental groundwork is already laid.
Can we fight all of Islam? No, not militarily. But what we need to do is to defend our ideas, because this is the area in which we really fall down. Western society has an entirely different basis, and is based on the concept of natural law and the value of the individual. It's hard for us to present this clearly because we have our own undermining force, Marxism, which is based, like Islam, on an externally imposed law (for the good of an entity known as the state, in this case), and exalts the collective.
But I think one area in which we are very remiss is the philosophical/theoretical area. We simply don't present it. About the only person who ever says anything regarding it is the Pope.
It would be nice if he had a little more company, because we need the two pronged approach: unrelenting military activity to protect ourselves and our allies, and vigorous philosophical/political activity to protect the core of our civilization and resist Islam at the most profound level.
IMHO, that's worth repeating.