The different religions are beautiful flowers from the same garden, or they are branches of the same majestic tree. Therefore, they are equally true, though being received and interpreted through human instruments equally imperfect.
--Mahatma Gandhi--
Probably 10 to 15% of the major terrorist organisations are Islamic in nature. On the other hand, it has been argued (see the above write-up by tusitala) that Islamic terrorists found their actions upon a relatively new interpretation of Islam, which is radically different from the interpretation which most Muslims grow up with.
If we accept the aforementioned statements, it results a link between Islam and terrorism, in which Islam could be a breeding ground for terrorism. However, this argument is not convincing. First, it is methodologically based on a small sample to verify a general hypothesis. Secondly, there are no new interpretation of Islam by Muslims. In fact, no religion in the planet, especially Islam, teaches terrorism or inspires any one to kill innocent people. Both the Qur'an and Sunna say that killing any person without a just cause amounts to killing the whole of humanity, and saving one person's life amounts to saving the entirety of humanity (1). Even the most radical supporter of Jihad, the revivalist arm developed by Sayyed Qutb, argues Jihad's goal is clearly to propagate the Islamic order worldwide. The tactics to achieve this resolution must not to be to coerce people to accept Islam, because the Qur'an encourages freedom of worship. Rather, it ought to be to overthrow un-Islamic regimes that corrupt their societies and divert people from service to God (2).
Perhaps the roots of the so-called Islamic terrorism are hidden among different and more complex causes, such as psychological disturbances, ethnic features, strongly rooted feelings of past glory, and globalization abuses.
The Islamic world has had its moment for glory and decline. For centuries, Arab scholarship played an important role in the development of academics in Western countries. Thereafter, the Crusaders' harassment, and overall the Mongolians' invasions in the 13th century were destroying Moslem cultural institutions, and eventually the Islamic golden age ended. This decline, and the further siege imposed by neoliberal economies, would determine feelings of humiliation (Muslims? Huh, you mean Mohammedans, these guys who're livin' in the Middle Ages...), instability and reduction of material well-being, all of which may have lead to 'chronic anxiety'. Such a societal crisis results in a behaviour whose goal is to protect its self-esteem and the ways of life remaining from Islamic civilization. Also, since a regular human response is blaming other of our own faults, the blame thrown against those allegedly responsible for the decline allows the individuals to feel connected and thus maintain a relatively high group's morale. Usually societies facing such kind of affairs languish, and very soon become pasture for developed countries (5).
Most Islamic terrorist leaders have some university education and come from rich families. For instance, Osama bin Laden inherited from his relatives hundreds of millions of dollars. If he wanted, he could enjoy luxuries, but he chose to fight in Afghanistan and live in caves (3). Mohamed Atta's will says 'When I die, I want the clothes I wear to consist of three white pieces of cloth, not to be made from silk or expensive material. A third of my money should be spent on the poor and needy' (4). These Arab terrorists know the brilliance and past glory of their civilization, and so they are more likely than illiterate masses to feel the 'chronic anxiety' which can be placated through the hostility driven against the perceived enemy.
However the responsible is powerful and cannot be defeated by means of a conventional -either political or military- approach. By the contrary, non-conventional ones (kidnapping, assassinating, bombing, or infecting) constitute an alternative to consolidate successfully that hostility: the terrorist action implies enormous difficulty to be predicted, and so to stand up for its atrocious consequences at global scale.
Terrorists are non-psychologically deviated individuals (3). It is likely that their 'strong morality' does not allow them to ignore the fate of their nation. As they consider themselves like elite members of Islam, they ought to confront by all means the enemies who are remorselessly harming their nation. This insight of conflict involves a solidarity of the poor, reinforced by religious conceptions (the unification of the Moslem world is the primary mission of Muslims ). Therefore this means that a Western attack on any Moslem country (Palestine included) constitutes an attack on the whole Muslim world.
For the Western countries the answer to 9/11-like attacks is 'preventive war'. However, even if most of terrorists are killed, this does not mean necessarily that terrorism can be eliminated. Whereas the social, cultural and psychological causes of terrorism remain, new generations of terrorists will arise.
References
1. Engineer AA (01/05/2003): Fundamentalism and Terrorism: Politics of Religion and Religion as Politics. http://www.tribuneindia.com/2003/20030105/spectrum/main3.htm.
2. Paz R (2002): Is There an 'Islamic Terrorism'? http://www.ict.org.il/articles/articledet.cfm?articleid=46.
3. McCauley CR, Segal ME (1987): Social Psychology of Terrorist of Groups. In Hendrick C (Ed). Review of Personality and Social Psychology, vol.9, pp.231-256. Beverly Hills, CA: Sage.
4. Atta M (1996): In the name of God all Mighty_Death Certificate. http://www.abc.net.au/4corners/atta/resources/documents/will1.htm.
5. Arab Information Center (1999): Introduction to Arab World. http://www.middleeastnews.com/intoarab101.html.