It is merely its loudest expression, in the form of Islamism.
The problem is strict adherence to unique dogmas, without applying the restraint of competing virtues to them. Wisdom is a compound process. We require several perspectives to yield the best available result. Sometimes this means we choose between good and better, sometimes between bad and worse, and occasionally we get to choose between good and bad. But as a general rule, there's a great deal of uncertainty in the value of any decision.
The problem with Islam currently is that many interpret its suras as an exclusive source of wisdom, that it is always right in all circumstances. Too many believe this. And the difficulty is that it seems to be baked into the cake.
The same problem applies to fundamentalists of all stripes, whether they are religious or follow a political creed. A society can cope with a few people thinking they are especially virtuous. But large populations of fanatics are toxic.