Zakisamsudin has posted his thoughts on The Making of Muslim Terrorists. To begin, he points out that they should be called Muslim terrorists, but not Islamic terrorists, because terrorism is not Islamic. I thank him for the distinction.
He then theorizes that Muslim anger originates in fellow-feeling within the Muslim umma, in the desire to alleviate the oppression of Muslims in various places around the world. But I think he overlooks the effect of culture on shaping the outward expression of that desire.
For example, Coptic Orthodox Christians are oppressed in Egypt. The latest outrage has been anti-Christian rioting in Cairo that resulted in a Church being stormed by a crowd of Muslims. Yet, I do not feel motivated to burn a mosque, or to get a gun and shoot into a halal restaurant.
In my culture it is forbidden to make someone pay for a crime he or she did not commit. This came about because we have developed a system of justice in which it is reasonably likely that the individual perpetrators can be found and prosecuted.
In many honor/shame cultures, the system of justice is much more "lightweight." Without an elaborate network of police, judges, courts, and prisons (all very expensive) these cultures leave justice up to clans and families. Since apprehending the perpetrators is more of a problem, the problem is made easier by allowing any of the perpetrator's clan or family to bear the punishment if they can be caught. The idea that revenge can be sought against any and all of the members of another ethnic group, nation, or culture is a modern extension of this old concept.
I'm glad to see that Zakisamsudin has read Ed Husain's The Islamist. But again, the story is not just psychological but the coming together of culture and psychology. Specifically Ed fell into extremism because he was trying to forge an authentically Islamic adult identity that was different from his parents' and dramatically distinct from the cultural identity that was offered by Britishness. He was thus caught between his partial understandings and fantasies of Islamic and Western culture. In his effort to become a man under such circumstances, he went part way down the path of becoming evil. Fortunately for him and for all of us, his God-implanted sense of right and wrong asserted itself, and he turned back. In the end, Ed forms an identity that is simultaneously (1) authentically Muslim after the pattern of his parents and the Islamic scholars they revere, and (2) authentically British with its embrace of free speech, thought, and inquiry, and its sense of honor and fair play.
The point of all this is that Muslim terrorism is not entirely a psychological phenomenon. It must be understood in the context of culture as well. Religion plays a part, too, but more as an identity-badge, not as religion per se. After all, the terrorists' psychology and culture lead them to commit atrocities that are specifically forbidden by their religion, and at the same time to lie to themselves about it. They do that which is forbidden and feel themselves to be holy witnesses, to be martyrs.