This raises the question: are some of the terrorists nut cases who seek out radical Islam in order to get in on the action?
Islam is a cult, not a religion. It takes over every aspect of the follower's life, tells him everything he must do, and sets him apart to live in a special, enclosed world.
People who are attracted to cults - ranging from some of the bizarre medieval cults that the Church was always trying to stamp out to modern things such as Jim Jones' group or the nuts who died in California with quarters in their pockets to make phonecalls from outer space - are generally immature, often permanently unstable, people who feel that normal life offers them no possibilities. The cult, on the other hand, makes them feel special, it gives them an identity, and it controls every part of their lives, relieving them of the need to make any decisions.
The attraction of Islam to people not brought up in it is precisely that. Mohammed was the L. Ron Hubbard of his day, creating a syncretist cult that installed him, initially, as its head but then passed the power along to his descendants. It is a cult that sees itself as both a religious system and a political system, a closed special society, and one that has any right to do anything it wants to extend itself and punish people who are not cult members.
The great majority of people who are unfortunate enough to be born into societies dominated by the cult honestly don't know any better, and when the cult's leaders feel they are too weak to attack, the cult is fairly quiet and its rank and file members are not called upon to act. However, modern weaponry - cheap and available - combined with the vulnerability of modern society, particularly in transportation (although attacking ships and caravans has always been a favorite Muslim pasttime) - have given the leaders new hope and this is the reason they are stirring up their people now.
And the clueless losers who normally join cults look at this and see the answer to all their uncertainties and dysfunctionality.