rom the moment americans learned that the 19 aerial assassins of September 11 were Muslim Arabs, they began to wonder: What did Islam have to do with it? The answers were plentiful and quick to come but often contradictory and confusing. Heads of Muslim nations and leaders of Islamic organizations around the world emphasized that Islam was incompatible with terror, violence, and intolerance. And the spirit of the oft-quoted line from the Koran, "Let there be no compulsion in religion," seemed to reassure most of America's religious, civic, and political leaders. "The face of terror is not the true faith of Islam," President Bush confidently announced after meeting with Muslim officials at Washington's Islamic Center the week after the attacks.

But if all that was true, why did so many inhabitants of the long Muslim "street" stretching from Morocco to Indonesia appear to be overjoyed by what Osama bin Laden's henchmen had accomplished? For that matter, why were certain Islamic jurists in Pakistan issuing religious verdicts, or fatwas, directing Muslims to fight American infidels if they attacked Afghanistan? Most disturbing, some of those same voices of moderation–even among those who met with Bush at the Islamic Center–had occasionally expressed their approval of Islamic groups such as Hamas and Hezbollah that engage in terrorism.

Scholars and experts, as they began to appear on the op-ed pages and talk shows, did little to resolve the contradictions. Often, they merely took them to a higher level. On one side, broadly speaking, were those sympathetic to the views of Princeton historian Bernard Lewis. The British-born scholar and author sees the events of 9/11 as the tragic consequence of a long conflict between the Islamic world and the West, a conflict largely dominated by the former until a little over 300 years ago when the Ottomans failed in their second attempt to take Vienna. Crediting bin Laden with a strong (if not altogether accurate) sense of history, Lewis argues that the al Qaeda leader gave expression to the "resentment and rage" of people throughout the Islamic world.

Strongly rejecting this reading of the problem are the experts associated with Columbia literature professor Edward Said, author of the influential book Orientalism. The Palestinian-American scholar charges that Lewis is one of those western "orientalists" whose oversimplification of Eastern civilizations has helped to justify European imperalism. Said insists that Islam is no "monolithic whole" but an internally divided body of competing "interpretations." It should be treated the same way Christianity and Judaism are, Said urges, "as vast complexities that are neither all-inclusive nor completely deterministic in how they affect their adherents." On such disagreements turned an even larger question: Was September 11 the outgrowth of a "clash of civilizations," in the words of Harvard political scientist Samuel Huntington, or was it, alternatively, the product of a struggle within a civilization?

Bewildering as all this was, Americans might have found it somewhat easier to negotiate if they had paid as much attention to the Arab side of the terrorists' identity as they did to the Muslim side. The friction between Lewis and Said loses some of its heat, for example, when 9/11, bin Laden, and al Qaeda are seen as key elements of a struggle that is taking place primarily within the Arab core of the Middle East. At the heart of this struggle is the political failure of the various Arab regimes that emerged after the defeat of the Ottoman Empire and the end of European colonialism. Those regimes–whether kingdoms, parliamentary democracies, or single-party socialist states–were all roughly designed after western models, with elements of western law. But all quickly devolved into despotic states, corrupt and generally incompetent in meeting the basic needs of their citizens. Not coincidentally, leaders of some of those states–notably, Egypt, Syria, and Iraq–for a time paid lip service, and perhaps something more, to a largely secular vision of pan-Arab political unity. A humiliating defeat at the hands of the Israelis in 1967 dashed that dream.

Quickly emerging in its stead was a highly politicized version of Islam–what scholars have come to call Islamism. Its leading ideologues, such as the Egyptian Sayyid Qutb (hanged in 1966 for allegedly plotting to assassinate President Gamal Abdel Nasser), advocated the rejection of all western political models and the creation of "pure" Islamic states run according to sharia, or religious law.

To some extent, this notion was as old as Islam itself, which in its classical form under Mohammed and his early successors (the caliphs) brooked no division of the political and religious spheres. But in practice, as Islam spread throughout the Med- iterranean world and into South Asia, divisions occurred. And religious law, far from being a simple set of prescriptive rules, was interpreted and elaborated by hundreds of schools of law and further tempered by local traditions and customs.

Throughout the history of Islam, however, there have been puritans–the medieval jurist Ibn Taymiya (1263-1328) was one–who demanded a return to the purity of the earliest caliphates, no matter how mythical this pristine condition was. But no puritan reformer has been more influential than the 18th-century Arab firebrand Muhammad ibn al Wahhab (1703-92). Critical of mainstream Sunni legalism, Sufi mysticism and philosophy, and anything smacking of "innovation," he forged a crucial alliance with the Saud clan, then engaged in a struggle with the Ottoman overlords.

The critics of Wahhabism, including many prominent Sunni jurists, saw it as a crude attempt to re-Bedouinize the religion by elevating the customs and practices of the desert Arabs (such as attitudes about the covering of women) into bedrock principles of the faith. Crude as it was, however, Wahhabism endured because of its ties with the Saud clan, which only strengthened over time through mutual support and intermarriage. In 1932, when the clan was established as the royal family of Saudi Arabia, the narrow, intolerant Wahhabist strain of Islam effectively became the established religion of the kingdom. And soon, with the Saudis' growing oil wealth, the Wahhabi religious establishment became one of the most richly funded and aggressive proselytizing bodies in the world, spreading an intolerant version of the faith that began to compete with other, more tolerant, and locally inflect- ed varieties of Islam. Notes Seyyed Vali Reza Nasr, a professor of political science at the University of San Diego, "The rogue states [such as Iraq and Libya] are less important in the radicalization of Islam than Saudi Arabia."

But if Islamism and Wahhabism emerged in the Arab core of the Muslim world, one of the ironic turns of recent history is that political Islam fared better beyond the Arab core than in it. An Islamic republic, albeit Shiite rather than Sunni, arose in Iran in 1979, and in both Turkey and Algeria Islamist parties became important political players (at least until the one in Algeria proved too successful and was suppressed by the military). In nations of the Arab core, by contrast, Islamists have been tolerated–and often modestly encouraged–to the extent that they posed no direct threat to the political regimes. Those individuals who take Islamist notions too seriously, including bin Laden (whose unhappiness about the Saudi kingdom's close ties with the infidel Americans is now well known), have faced exile or worse. But, as the world has learned, those outcast Islamists have learned to operate quite effectively in strange lands, whether in Afghanistan or Europe or even the United States.

Is Islamism, then, a clear and present danger–to the United States and to the world in general, including its 1.2 billion Muslims? The answer might seem obvious in light of the havoc wreaked by a band of Islamist zealots on September 11. To the extent that it nourishes and encourages fanatical hatred, it clearly is a danger. And as Johns Hopkins University international security specialist Michael Vlahos argues in his cogent study, "Terror's Mask: Insurgency Within Islam," Americans must be forthright in naming their foe. It is not some nameless "terrorism," Vlahos says, but a dangerous movement within Islam.

This Islamist insurgency is certainly not all of Islam. And in his book, Jihad: The Trail of Political Islam, the French scholar Gilles Kepel makes the persuasive case that Islamism itself has split into moderate and extreme elements, with the former championing various notions of Muslim democracy and the latter resorting to violence and terror to bring about totalitarian theocracies. Indeed, Kepel finds that September 11 was a last-ditch effort on the part of Islamist extremists to revive their waning movement. "In spite of what many hasty commentators concluded in its aftermath," Kepel writes, "the attack on the United States was a desperate symbol of the isolation, fragmentation, and decline of the Islamist movement, not a sign of its strength and irrepressible might."

Perhaps. But even if true, Kepel's analysis offers little comfort to the victims of this desperate insurgency within Islam. And even if extremist Islamists are only a minority within Islam, no one should forget the lesson of the Russian Bolsheviks: Determined minorities sometimes win.