We are now approaching a religious season of peace and good will. The Jewish festival of Hanukkah, the Feast of Lights, celebrates a victory of faith over the forces of irreligion. At Christmas, Christians will celebrate the birth of the Prince of Peace. Yet this is a time of darkness and fear. Not only are we living in an atmosphere of violence and cruelty, but the people who are terrorising the world do so in the name of religion. Since the attacks on the twin towers and the Pentagon, we have witnessed more suicide bombing in Israel and Palestine, the killing of Indian Muslims by Hindus, the siege of a Moscow theatre by Chechen rebels, killing and the burning of churches in Nigeria, and bombings in Bali and Mombasa.
What has happened to religion since 11 September? The September apocalypse was a revelation. During the 20th century, a militant piety, often called "fundamentalism", had erupted in every major religious tradition. It was a widespread rebellion against secular modernity. Wherever a western-style society was established, a religious counter-culture grew up alongside it, determined to drag God or religion from the peripheral position to which they had been relegated back to centre stage.
Every fundamentalist movement that I have studied in Judaism, Christianity and Islam is rooted in a profound fear of annihilation; fundamentalists are convinced that modern, liberal society wants to wipe them out. Most simply retreat into embattled enclaves where they can live a truly religious life. They also try to give religion a higher profile in public life: Muslim fundamentalists establish welfare movements; Lubavitcher Hasidim try to reclaim secularised Jews for the faith; American Protestants campaign against abortion and try to reform school textbooks. Except in regions where there is already an established conflict, the vast majority do not resort to acts of terror and violence.
By the year 2000, however, it was clear that, in all three faiths, a dedicated minority was reaching for more radical solutions. Al-Qaeda has simply taken fundamentalism another step forward, impelled no longer by fear and despair, but by righteous rage. Most Muslims, fundamentalist or mainstream, have not endorsed Osama Bin Laden's campaign. They may deplore the apparent bias of the United States towards Israel, the American-led sanctions on Iraq that have killed hundreds of thousands of civilians, many of them children, and US support for unpopular and despotic regimes in the Islamic world, but most Muslims continue to adhere firmly to sharia, which forbids the killing of innocent civilians.
If, however, there are further civilian casualties in the "war against terror", more Muslims may well despair of a conventional political solution and join the extremists. In the past, every attempt to suppress a fundamentalist movement has made it more radical and intransigent. Aggressive methods of repression simply confirm fundamentalists in their fear of annihilation. At present, for example, every Israeli reprisal leads to a new spate of suicide bombings: the result is an apparently unstoppable escalation of secularist and religiously inspired violence.
In the west, our view of Islam is deeply coloured by events in the Middle East, and most of the terrorism that disturbs us in the current crisis is Arab. But Arabs comprise only 20 per cent of the Muslim population worldwide. To their credit, both George W Bush and Tony Blair have insisted that Islam is a peaceful and benevolent religion, but there is a rumbling suspicion - often confirmed by irresponsible media reporting - that Islam is inherently violent, intolerant and opposed by its very nature to democratic, modern society. This is extremely dangerous. Once Muslims get the idea that the west has demonised Islam and wants to get rid of it, extremism is likely to become more widespread.
In the United States, the religious right is doing its best to inflame American suspicion of Islam. Its leaders are preaching a gospel of hate to audiences of 5,000 and more. Islam, according to Franklin Graham, the son of Billy, is an "evil and wicked religion". Jerry Falwell recently denounced the Prophet Mohammad as a terrorist. The popular columnist Ann Coulter has urged the US government to "invade [Muslim] countries, kill their leaders and convert them to Christianity", while the conservative writers Paul Weyrich and William Lind argue that American Muslims "should be persuaded to leave. They are a fifth column in this country."
Officials and observers fear that, in the event of another major attack against America, it might not be possible to control the growing hatred of Islam, which is being marshalled so successfully by the Christian right. There is already talk of Arab- Americans being interned or deported, and if this should happen, the anger on the streets of the Muslim world will be horrific. We have long been aware that religious fundamentalism can jeopardise a peace process - we need only think of the fate of Anwar Sadat and Yitzhak Rabin, both assassinated by fundamentalists on their own side. But since 11 September, we have become aware of how small groups will increasingly have powers of destruction that previously belonged only to nation states, so this religious menace is now far greater.
What has mainstream religion done to counter the danger? In the US, there have been inspiring examples of interfaith co-operation since 11 September. In one small town in Ohio, for example, a church offered to form a human chain around the local mosque to prevent hate crimes. They expected only a couple of hundred people, but 2,000 turned up. Many Americans now recoil from narrow sectarianism. Churches have invited Muslims and Islamists to discuss the crisis and to teach Christians about Islam; sometimes people drive hundreds of miles in order to attend such a gathering. Muslim and Jewish peace initiatives have sprouted in both America and the Middle East, and I am engaged in a Muslim project to develop a vibrant, tolerant but truly American Islam - a bridge, it is hoped, linking east and west.
But many religious people have not responded to the wake-up call of 11 September, and have remained stuck in their old sectarian positions. In the Roman Catholic Church, for example, as the scandal of sexual abuse has grown, some in the hierarchy have seemed more concerned about the integrity of the institution than about the truth or compassion for the victims. Many Muslims, in fear of western reprisals and profoundly disturbed by what has been done in the name of their religion, have simply retreated to the mosques, and have not been sufficiently forthcoming in condemning the atrocities; some Jewish communities, equally disturbed by unfolding events, denounce every criticism of Israel as anti-Semitic.
The events of 11 September revealed the dark side of globalisation, so it is not surprising that some religious people have responded to the crisis by drawing in their horns and becoming more tribal. But it is not sufficient for the official faiths simply to denounce this wave of religious terror verbally. In their fear and rage, fundamentalists tend to distort the very tradition they are trying to defend, especially by exaggerating its belligerent elements and downplaying those that insist upon respect for the sacred rights of others. Religion itself was hijacked and discredited on 11 September, and it must now be reclaimed by a compassionate offensive which shows that religion can make a difference to a world torn apart by hatred and fear.
But there is another form of fundamentalism, especially rampant in Britain, which must also be held in check. A few days after 11 September, an acquaintance rang me in triumph to declare that God was finally dead. Last week, a young girl denounced me for my interest in religion in almost exactly the same terms as, a few years ago, a student in the Bible belt attacked me for interpreting scripture in a non-literal manner. This is secular fundamentalism, and it can be just as partial and prejudiced as its religious counterpart.
Not all religion is good; there is bad religion as there is bad art, bad cookery and bad sex. To see Bin Laden as typical of religion is as inaccurate as to equate all secularism with Stalin. What has happened in Washington, New York, Bali and Mombasa is a vile perversion of religion, but it does not represent the whole. Indeed, this type of secularist disdain is one of the factors that caused religious fundamentalism to develop in the first place. Every fundamentalist movement that I have studied began with what was perceived to be an assault by the liberal establishment, and each has developed in a symbiotic relationship with an invasive, aggressive secularism.
One of the revelations of 11 September was that we live in one world. Events that happen today in Gaza or Iraq will have repercussions tomorrow in London or New York. Fundamentalist ideologies may have looked crazy to an outsider, but they were trying to express fears that no society can safely ignore. In the post-11 September world, we can no longer isolate ourselves in religious or secularist camps, gazing at each other with hatred and contempt, because we have learnt to our immense cost that such attitudes are no longer merely parochial, but also dangerous.