Furnish, who teaches at Georgia Perimeter College in Atlanta, has written a deliberately provocative narrative about apocalyptic movements in Sunni Islam with the stated intention of ignoring the central role of belief in a mahdi or Islamic messiah in the Shi‘i sect. His reasoning on this matter, which seemed quite daring in the immediate aftermath of September 11, 2001, was dual. First, he was interested in whether Osama bin Laden might consider himself, or be considered, a mahdi figure, and, second, he expressed his dismay that Western studies of Shi‘i Mahdism are available in plenitude while Sunni Mahdism has tended to be ignored.

The author's predictive thesis is stated without reservation: "contra conventional wisdom in the field, belief in the Mahdi is as vital in Sunni as in Shi‘i Islam." Unfortunately, history has favored conventional wisdom over this interpretation. While eschatological or "last days" rhetoric may be more common in radical Sunnism these days than among Shi‘a, the title of Mahdi has not returned to the attention of the West because of bin Laden, who shows no interest in proclaiming himself as such, or any other Sunni figure. Rather, the term has reentered the global vocabulary because of the apocalyptic rhetoric of Mahmoud Ahmadinejad, president of the Islamic Republic of Iran, and the actions of the radical Shi‘i militia known as the Mahdi Army, headed by the Iraqi demagogue Muqtada al-Sadr. A serious, detailed, and comprehensible look at Shi‘i beliefs about the twelfth imam and his occultation and how they play out in the speeches of Ahmadinejad as well as the armed intrigues and depredations of the Sadrists, would be extremely useful to Westerners right now.

This book, however, deals only with Sunni aspirants to mahdihood. Its value resides in its original treatment of Sunni mahdist and counter-mahdist patterns, which turn out to be quite cohesive over space and time. Furnish discusses two of the most significant chapters in Islamic history, the Muwahhidun and the Sudanese mahdi. Known to the West as the Almohads, the former were believers in an extreme form of monotheism who appeared in the twelfth century C.E. after they swept out of North Africa and conquered Islamic Spain. The nineteenth-century Sudanese mahdi, Muhammad Ahmad, succeeded in defeating the combined forces of the British and Ottoman empires.

While Furnish makes the case to pay more attention to Sunni Mahdism, only time will tell whether this phenomenon will prove more important, globally, than the hallucinations of an Ahmadinejad.