By the middle of the 20th century, pundits and intellectuals in the West generally took it for granted that secularism was the coming ideology and that religion would never again play a major role in public life. However, within a few years, it became clear that a militant piety had erupted in every major faith, dragging God and religion back to center stage from the sidelines to which they had been relegated. The 1979 Islamic Revolution in Iran showed the potential of this new form of faith. Western observers were astonished to see an obscure mullah overturning what had appeared to be one of the most progressive countries in the Middle East. “Who ever took religion seriously?” cried a frustrated official in the US State Department shortly after the revolution. But the United States itself had recently witnessed the rise of Jerry Falwell and his Moral Majority, and a radical religiosity fueled the Arab- Israeli conflict on both sides.

Despite these symptoms, the secularist establishment struggled to understand what was happening, even though it was clear that this so-called “fundamentalism” was becoming ever more extreme. The atrocities of September 11, 2001, showed that the West can no longer afford the old secularist disdain for religiously inspired politics, and that scholars must now study fundamentalism as attentively as any other ideology.

“Fundamentalism” is an unsatisfactory word. Conservative Protestant theologians coined it in the early 20th century to describe their reform movement: they wanted to go back to the “fundamentals” of the faith. But people in other religious traditions complain when this Christian term is applied to their own movements. Protestant fundamentalists, they argue, were chiefly concerned about dogma and theological belief, while Jewish or Muslim traditionalists have different priorities. Nevertheless, despite its inadequacy, the term fundamentalism has become a shorthand way of referring to a broad band of religious movements in all the major faiths that bear a strong family resemblance. While this short survey shall be confined to fundamentalism in Judaism, Christianity and Islam, it is important not to forget the fundamentalism that has erupted in Sikhism, Hinduism, Buddhism, and Confucianism. There is also a form of secular fundamentalism, which opposes all forms of faith as belligerently as religious fundamentalists attack secularism.

Religious fundamentalism represents a widespread rebellion against the hegemony of secularist modernity. Wherever a modern, Western-style society has been established, a religious counterculture has developed alongside it in conscious rebellion. Despite the arguments of politicians and intellectuals, people all over the world have demonstrated that they want to see more religion in public life. The various fundamentalist ideologies show a worrying disenchantment with modernity and globalization. Indeed, every single fundamentalist movement that I have studied in Judaism, Christianity, and Islam is rooted in a profound fear of annihilation. All are convinced that the modern, liberal, secular establishment wants to wipe out religion. Each fundamentalist group has sprung up independently; each even differs significantly from other fundamentalists within their own faith tradition. But at the root of all these movements is the same visceral dread that is rapidly being transformed in some quarters into ungovernable rage. This should not surprise us; culture is always contested, and the proud secularism of Western modernity was almost bound to inspire a strong religious reaction.

Not all religious conservatives are fundamentalists. The US evangelist Billy Graham, for example, is not a fundamentalist; he would not describe himself as such, nor would he be accepted in fundamentalist circles as one of their own. Graham has always been prepared to work with other Christians, while fundamentalists are more radical separatists.

Fundamentalist movements usually follow a similar pattern in all three faiths. First, they take issue with their own co-religionists, who, they feel, have made too many concessions to modernity and are collaborating with the enemy. Fundamentalism always begins as an intra-religious dispute; only at a secondary stage, if at all, does it attack a foreign foe. Second, fundamentalists withdraw from the mainstream to create an enclave of pure faith in what they see as a godless world. Examples of these embattled religious havens are the ultra-Orthodox Jewish communities in Jerusalem and New York or the ultra-Christian Bob Jones University in South Carolina. The original impulse behind these communities is defensive, but from these sacred enclaves, some plan a counter-offensive against the political or religious establishment.

These counter-offensives are by no means always aggressive assaults. Only a tiny proportion of fundamentalists take part in acts of violence or terror. Most are simply engaged in an uphill struggle to lead what they regard as truly religious lives in a society that seems essentially and irredeemably hostile to their faiths. Protestant fundamentalists in the United States, for example, confine themselves to peaceful and law-abiding campaigns to expunge liberal or “heretical” views from school textbooks; the Lubavitcher Hasidim have launched an outreach campaign to bring secularized Jews back to religious observance. But because all fundamentalists feel so profoundly threatened, they are convinced that they are engaged in a battle with the powers of darkness. When people fight for survival with this absolutist perspective, they can lash out violently.