Read the whole thing.
The Totalitarian Present: Why the West Consistently Underplays the Power of Bad Ideas
As uncomfortable as it may make some tolerant and well-intentioned souls, an intellectually respectable case can be made that radical Islam constitutes the third variant of totalitarian ideology politics in modern history. The first version emerged in fascist Italy and Nazi Germany. The second was that of modern communism in the Soviet Union and elsewhere. While these first two versions succumbed to military might and ideological exhaustion, respectively, the political, ideological and military battle with radical Islam remains undecided.
One way to illustrate the case for radical Islam as Totalitarianism Mark III (and perhaps draw some practical conclusions from it), is to focus on three points of comparison and contrast between the Nazi and communist eras and that of contemporary political Islam: the problem of underestimating the power of ideology; modernity and anti-modernity; and the issue of preemption in context.
He partially blames liberal "sophisticated" thinking as one reason that the Islamist threat is not taken as seriously as fascism and communism was, but I would venture to say that much of it is simply that Islamism as a political ideology cloaks itself in religion, and most liberals don't want to challenge religious thought as much as they would like to challenge political ideas. If the separation between Islamism as a political movement and Islam as a personal religion could be explained better, then liberals would come around to the fact that they are against everything that political Islam is for.