I notice the left/right parameters for debate about the Muslim world leave little room for anything but a shouting match about whether or not this or that dude being Muslim actually matters. What about being a psychologist/psychiatrist and/or the influence of Communism? One has to get beyond the headlines and get pretty deep into some Middle Eastern story or another to notice various socialist and communist groups are alive and running around acting all para-military like in various parts of the Middle East. In addition, though one could argue it's just coincidence, at various times and various people involved in terrorism appear to have connections with the field of psychology- from Al Queda leaders to this Nidal character.
Communists, of course, went above and beyond everyone in terms of murdering people for their cause. In psychology the ideology of victim-hood is well-preached. Perhaps these secularizing influences have far more to do with terrorism than Islam does. A religious person may feel the need to die for his beliefs; he may feel it necessary to defend his land and people from attack, but it takes a certain positivist ideology to find and murder people who present no real threat.
In fact, the Tamil Tigers, a completely secular operation, invented suicide bombers; one can infer, then that Muslim beliefs about a suicide-bomber's great reward in heaven may make the job a bit more appealing, but isn't relevant to the decision to go forward.