Confusion is almost the point. Confronted by Islam in all its dizzying diversity, readers may begin to feel like Whirling Dervishes themselves as old stereotypes suddenly fly from their grasp. Armstrong’s theme is that centuries of conflict between the West and Islam (not to mention centuries of entertainment from Mozart operas to Hollywood movies that feature fiendish Saracens and narrow escapes from cruel sultans) have produced an archetypal Muslim in Western minds. He’s at once intolerant and indolent, despotic and submissive, puritanical and sensual, crafty and primitive, capricious and fatalistic. Above all, he’s a religious fanatic. Any progress in overcoming this image was presumably set back years on Sept. 11 — which is why a book like this is suddenly essential.

In Armstrong’s brisk narrative, the clichés evaporate fast. Islam advocates the enslavement of women? The Prophet Muhammad, as was customary, took numerous wives, but he broke with the harsh treatment of women that prevailed in seventh-century Arabia by giving them considerable respect and freedom. And the Koran — the Islamic scriptures — gave women rights to divorce and inheritance long before Christian Europe did. Jihad? Armstrong says it’s properly translated as ”effort” or ”struggle,” not ”holy war.” And, she adds, the Koran justifies defensive war but ”does not sanctify warfare.” The Arab conquests that created an Islamic empire from Spain to Afghanistan after Muhammad’s death in 632 were not primarily driven by religious motives, the author insists, and the Koran insists ”there shall be no coercion in matters of faith.”

Armstrong doesn’t neglect the dark side of Islamic History, which she notes contains about as many massacres as the dark side of Christian history. But what makes the book so appealing is that it doesn’t reduce Islam to its dark side or any other side. And she finds that Islamic fundamentalism has more in common with other fundamentalisms, including Christian and Jewish, than with Islamic traditions. All, she argues, are modern ideologies born of hatred and fear of modernity — science, individualism, the independence of women. All invent purified versions of the faith that have little to do with authentic origins and practices. Armstrong ascribes the particularly virulent form fundamentalism has taken in the Islamic world to the desperation aroused by the combination of Western secular culture and oppressive Middle Eastern dictatorships. And she points out that Islam’s deepest precepts mix up God and history (and God and politics) more than any other world religion, which can be a formula for fanaticism. But all religions have their demons to overcome, and her history shows that Islam is capable of overcoming its own, even now, when it finds itself with an ungodly number of them.