Like all fundamentalists, Osama bin Laden was attuned to the past. When his speeches weren't about the economic decline of America, they recalled Islam's classical age, especially the rise of the Prophet Muhammad through the Rashidun ("rightly-guided") period, which ended in 661.
Bin Laden saw himself as an Islamic Martin Luther: a protestant who was willing to go to war with the Muslim world's Westernized, U.S.-aided kings and presidents-for-life. He hoped to arouse, by the strength of his example, a global movement that would drive the U.S., the cutting edge of the West, out of the Muslim world. Showing American feebleness would bring the inevitable collapse of the unrighteous and the restoration of a more virtuous age.
He sustained himself for so long in the Middle East and Central Asia because lots of Muslims—especially in powerful places in Sudan, Saudi Arabia, Afghanistan and Pakistan—were sympathetic to his cause. For a time, he tapped into an angry, shameful intellectual current among Muslims, who after World War II were increasingly immiserated by their ever more lawless rulers.
The Westernized police-states (Egypt, Syria, Algeria, Tunisia and Libya) and the corrupt "Playboy" monarchies (Saudi Arabia, the Gulf Emirates, Jordan and Morocco) all became breeding grounds for violent fundamentalism. And even among most Muslims, who did not drink deeply of this creed, the spiritual depression and conspiracy-mongering of these societies made bin Laden an admired celebrity, if not a hero, since he at least scared and hurt the all-powerful United States and openly belittled the detested autocrats.
Historically, Islamic societies have had a fairly high tolerance for the use of violence for a just cause. Bin Laden knew well the line of thought that sees rebellion against unjust rulers as a moral obligation. This was a defining theme of early Islamic history, when Muslims as a community wrestled with what constituted legitimate authority after the death of the Prophet Muhammad.
Among the Arabs, Princeton's Michael Cook has written, "political and military participation were very widely spread, far more so than in the mainstream of human societies—whether those of the steppe nomads, the later Islamic world, or the modern West. It was the fusion of this egalitarian and activist tribal ethos with the monotheist tradition that gave Islam its distinctive political character. In no other civilization was rebellion for conscience sake so widespread as it was in the early centuries of Islamic history; no other major religious tradition has lent itself to revival as a political ideology—and not just a political identity—in the modern world."
Bin Laden, who believed that only the most virtuous had the right to rule over the community, was undone by his love of violence. He pushed it too far: Slaughtering innocent Africans in Kenya and Tanzania in 1998 was tolerable since the targets were American embassies (and black Muslim Africans were too far from the Arab world to compel a scathing moral critique). Killing American sailors on the USS Cole in the port of Aden was praiseworthy since no modern Muslim power had ever so humbled an American man-of-war. And destroying the Twin Towers and punching a hole in the Pentagon was just astonishing.
But then came the slaughter that could not be ignored, as al Qaeda affiliates started killing in Muslim lands. The suicide bombers who hit Casablanca in 2003 and Amman in 2005 made an impact. But the war in Iraq was bin Laden's great moral undoing.
Iraq was supposed to be where al Qaeda and other "good Muslims" broke the American back. Instead the carnage there, carried in all its gore by Arabic satellite channels, produced a backlash. There was a limit to the number of Shiite women and children that Sunni Arabs could see murdered. Blowing up hospitals, mosques and shrines—even Shiite ones—became too ghastly to sublimate into an acceptable war against the Americans.
Al Qaeda had helped to provoke one of the worst bloodlettings in contemporary Arab history. Voices within Islam began to rise against its ruthlessness. Ayman al-Zawahiri, al Qaeda's intellectual, knew that his kind had gone too far, but there was little that he or bin Laden could do once the jihadist beast had been let loose.
In Iraq, al Qaeda effectively became a takfiri movement: Holy warriors "legitimately" slaughtered other Muslims because they deemed them no longer Muslim but kuffar, infidels, who may be killed in conflict. Bloody takfiri movements can outlast one inspirational leader, but they never win.
It's entirely possible that if the Taliban win in Afghanistan, al Qaeda could get a new lease on life. The Pakistani and Afghan Taliban movements have absorbed much of the ideology that ignited al Qaeda in the early 1990s. The operational support—free passage and refuge—that Iran gave to al Qaeda before and after 9/11 is probably still there if al Qaeda can organize itself into an effective strike force, especially against Saudi Arabia. And Zawahiri has long been Tehran's favorite Sunni holy warrior. He certainly has the ability and perhaps the means to maintain al Qaeda's global networks.
But networks must be nourished. If this spring's great Arab Revolt continues—if the brutalized societies of the Middle East can establish more lawful, representative governments, if their ethics can recover from the years of powerlessness, shame and conspiracy—then al Qaeda will surely lose its future among the Arabs.
It may raise its head now and then. If it could get its hands on the right type of weapons and the deranged young men to use them, it could still kill on an impressive scale. But the group will most likely wither, perhaps rapidly, as Sunni Arabs construct a moral universe in which militants can no longer compellingly call upon Islamic history to justify rebellion. Bin Laden understandably loathed democracy: It's the end of the political and ethical order where his world makes sense.
Mr. Gerecht, a senior fellow at the Foundation for Defense of Democracies, is the author of "The Wave: Man, God and the Ballot Box in the Middle East" (Hoover, 2011).