In the conventional political narrative the root causes of Islamic terrorism usually run the class warfare gamut from the generic oppression to outrage at Western foreign policy or more esoteric issues of globalism. And naturally like most people who look into a mirror to find the cause of someone else's anger, their reflection only repeats back to their own agenda.
While Western liberals insist on viewing terrorism as a form of political or social activism, within the Muslim world terrorism is a two-sided tool, a way to create friction with an enemy without going to war while promoting the political standing of its leaders and backers. This two-sided concept of terrorism goes back to the nomadic days of bandit raiders that would carry out hit and run attacks that would bring in loot while raising the status of the tribal sheikh and the head of the raiding parties. Given enough time probing the enemy's weakness and raising the stature of the sheikh, such attacks might escalate into all out wars. And while such tactics may seem primitive, Mohammed was able to leverage them to turn his newly created Islamic cult into a major player in the region.
In modern times, the driving ideological force behind Arab-Muslim terrorism has been to recreate a single great state to replace the splintered colonial entities left behind by the destruction of the Ottoman Empire. It was an ancient tribal goal, and one that Mohammed's followers had come closest to achieving in the Arab version of the Thousand Year Reich. Modern versions of this might vary from the Islamic Caliphate to the secular Arab Nationalist version that would be a Socialist dictatorship run by someone like Nasser or Saddam. So while the ideology might vary, the underlying idea was always the same. One great state under one great ruler, who would demonstrate his fitness to rule by subjugating the enemy and thereby bring all of the region under his rule.
Under the ancient raiding codes, showing the most boldness and inflicting the most damage by striking at the enemy demonstrates that fitness to rule. This form of Arab-Muslim internal rivalry routinely spills over into external wars and terrorism, as both sides seek to prove their superiority by killing as many infidels as possible.
So Osama bin Laden's tribal religious conflict with the Saudi rulers was fought with the Soviets and then with America and Europe, more than with the House of Saud itself. Using the pretext of the US troops that the House of Saud had brought in to protect themselves from Saddam, Bin Laden was able to gain religious imprimatur for a war on America to build status for his claim to rule over the holiest place in Islam. The Saudis in turn had been funding a covert war on America for the same reason, as well as to divert wannabe Bin Ladens from trying to seize power.
In the same way Hamas and Fatah addressed their rivalry for nearly two decades by competing to see who could kill more Israelis. Hamas' greater viciousness and murderousness won it the support of Palestinian Arabs, allowing them to triumph in elections and seize Gaza. While Western liberal observers have struggled to frame the conflict in terms of Hamas' social services or Fatah's corruption, these were only side issues. The main event was to demonstrate who could inflict more harm on the enemy. An indirect conflict the Arab Nationalist Fatah and the Islamist Hamas for power over the Palestinian Authority cost the lives of numerous Israelis and foreign tourists, and it had next to nothing to do with any of the usual propaganda complaints about checkpoints or the wall of separation or even the desire for a Palestinian State, which the terrorism repeatedly sidelined. It had to do with an internal conflict expressed indirectly, a problem that is the root cause of much of Islamic terrorism.
That problem is also why there are fairly few actual moderate Muslims. When showing strength or inflicting harm against the enemy is key to leadership, moderation is an express train to nowhere. As terrorists have repeatedly demonstrated, every single Islamic religious law and practice can be set aside in the interest of killing infidels. That is because in practice no Islamic virtue is greater than that of defeating infidels and heretics. That singleminded approach allowed Islam to expand from an obscure cult to an empire. If Judaism embraces study and Christianity embraces evangelism as their key attributes, Islam embraces conquest. There would be no Islam without conquest. There can be no Islamic expansion today without it.
Within this framework, terrorism allows different groups to jockey for power by demonstrating that their way is best, when it comes to that fundamental virtue of killing infidels and forcing them to submit to their authority. All the while avoiding an open and outright war, which they are certain to lose. Terrorism allows Arab and Muslim nations to carry on covert wars, and allows for the rise of local chiefs who conduct those wars, from the late and unlamented Yasir Arafat to Osama bin Laden, Nasrallah or Muqata al Sadr. Virtually every part of the world today has such chiefs or wannabe chiefs whose followers carry out bombings and murders in their name.
While the local pretexts may vary, Western observers err by confusing the propaganda with reality. Hitler did not invade Poland for any of the reasons he claimed he did, no more than Japan invaded China to protect the region from Europe. Like the mythical raped Belgian nuns of WW1, propaganda is not motive, and it is startling to note the great eagerness with which supposed regional analysts treat propaganda as motive, rather than pretext at best.
But that dream requires leadership, and that struggle for leadership has also indirectly led to much of the terrorism in the 20th century and the 21st, as Arab leaders and Islamic militias have all struggled to define the cause around individuals. Osama bin Laden's videos, like Arafat's infamous speech at the UN, are part of that larger narrative, a story of "personal greatness" weighed by the value of the only coin acceptable in the Middle East and demonstrated through the corpses of innocent men and women who belong to the "tribes of the enemy".