"Immense implications" is the kind of phrase most of us would use to describe the kind of consequences we expect to follow the large-scale attacks on America on September 11th. But how immense, and in what specific directions? The whole world is trying to see through the fog, and with an intensity that perhaps has no precedent since the first use of the atomic bomb in Japan in 1945. In some ways, "Manhattan", "Horror Tuesday", "Ground Zero" — or whatever nickname may come to specify it in future history classes to rival Marathon, Waterloo and Pearl Harbor — can be argued as probably more significant than Hiroshima and Nagasaki put together. Whereas those two cities were destroyed during a formal war by a major state with huge industrial capability and legal responsibilities in the world, the destruction of the centre of New York and its subsequent crippling of the American economy were accomplished by a small band of outlaws with no weaponry except America's own passenger aircraft laden with America's own aviation fuel. In other words, today many more people are capable of posing a major threat to society than are the governments that possess nuclear weapons.

As I write these lines, the November issue of Britain's Prospect magazine has been published. Its cover speaks volumes in a few words that would have been impossible in a liberal publication three months ago. "The West Wakes Up", it says. Other commentators have talked of "the war of the worlds", outdoing Samuel Huntington's mild — and yet derided — "clash of civilisations" in 1996.

So, what kind of consequences might we expect over the next few years and in the longer term? To begin with, a much less free society than we are used to here in the West. Judging by the first, unofficial outlines of new legislation being mooted by the British government, all criticism of Islam will, in the future, be minutely examined by government lawyers for signs of offending Muslims and thus "inciting religious hatred". The legislation will be extended to cover all religions, so that the Government can claim to be neutral between them, and I can envisage many courageous people among us going to jail once more in Britain to gain freedom of expression for the country. Many more of us will oppose the Government's plan before it becomes law, on the grounds that it is unnecessary, and that, while it gives in to the terrorists, criminal legislation already covers all incitement to public disorder. If the legislation extends the currently-redundant blasphemy laws to include Islam and the other non-Western religions, some of us might even apply to the courts to ban the publication of all holy books on account of their blaspheming against one another! Surely, what we need is to scrap the blasphemy laws altogether.

Other areas of our freedom we will surrender more readily, because the majority of us will be realists. Governments have no alternative now to giving huge sums of new money and wide licences to their intelligence agencies to listen to our telephone conversations, open our letters, intercept our emails, look into our bank accounts, gather information about our beliefs, stop us on the streets to check our identities, spy on our friends and file our movements. This will be primarily aimed at people like me, with connections to the Middle East, but the legislation will be non-discriminatory and therefore, almost certainly, abused. Majority public reaction is likely to be one of resignation, for if you have nothing to hide, why fear the spies who are trying to make us safe? Perhaps Orwell should have called his famous novel 2004. A by-product will be a vicious circle which will produce more extremists from among the Muslim populations already settled in the West. Even before the horror of September, 'Islamophobia' was well documented and on the rise. The events of September have made it worse and, now, press reports that "hundreds" of Muslims born in Britain have gone to Afghanistan to fight against their own country will make the antipathy even deeper. Enhanced police surveillance of Muslim lives is bound to make many more of them feel they do not belong here. Urban areas such as Oldham in the North of England, which were already out of bounds to whites, will become walled enclaves reminiscent of the Jewish ghettoes of medieval Europe.

Curtailed civil liberties at home, however, can hope at most to reduce the threat of the New Terrorism. Unless all travel from the Islamic world to the West is banned — which will be impossible — some terrorists will still manage to penetrate the fortress. At the very least, the terrorists have learnt that the occasional posting of a gram of anthrax from obscure corners of the world will inflict panic on large sections of Western society, and that even a tiny amount of wheat flour will close a major institution for days, with all the economic damage which that entails. Billions of pounds of money needed for hospitals and schools will be channelled into employing more policemen and buying new gadgetry to watch and prod the citizenry.

More people will accept the argument that refugees and unwanted migrants from non-Western cultures should be locked up in detention camps for long periods to deter others. Academic research published in late October suggested that, if recent trends continued, Islam would become the largest religion practised in Britain in 40 years' time. The events of September will probably have put an end to such trends for the time being and, indeed, we may expect that mainstream political parties will swerve to the right to prevent any vacuum from coming into being that might be filled by the smaller parties of the extreme Right. If this does not happen, there is every likelihood that we will witness the return of fascism to power in at least several European states before too long.

Perhaps the most important question on everyone's mind is whether the crisis represents a new Hundred Years' War, though this time between the West and the world of Islam. To say that the Al Qaidah movement of Osama bin Laden, almost certain to have been behind the attacks, has nothing to do with Islam is clearly not convincing. While we understand the proclaimed hopes of politicians like president George W. Bush and Prime Minister Tony Blair that it has not, why is it, asked the historian Felipe Fernandez-Armesto on BBC Radio 4 in late October, "that all those on one side are Muslims?" Furthermore, while we may dismiss bin Laden as a psychological case, as I did on the same programme, why is it that millions of Muslims everywhere have made him a hero? How is it that the editor of Al Ahrar, a so-called liberal newspaper in Egypt, can bring himself to say that it is "our religious and national duty to rejoice" at the death of all those Americans? Why is it that the editor of Syria's main literary weekly, Al Osbu Al Adabi, can dare say that his "lungs filled with fresh air as they had never done before," on seeing the towers of the World Trade Center in Manhattan crash to the ground? What happened to the humanity of these people? If this is not a clash of civilisations, if it does not represent the collective wish of the Islamic world to bring down the house of its old European rival, then what is it?. Does any disagreement with the foreign policy of a foreign power — say over Israel — give anyone the moral licence to go and blow up one of its cities?

Yet another proof that the Islamic world does not appreciate the enormity of the crimes of September came a month later when only one Muslim country, Pakistan, agreed to help America and Britain in their military operations to destroy the bin Laden organisation and the Taliban regime that sustained it in Afghanistan.

But even here, the military dictator of Pakistan agreed to cooperate only after he had been told that his air force would be destroyed and his country made defenceless against India if he stood in the way of the operations. Even the kingdoms of Oman and Saudi Arabia, whose very survival against such fellow Muslims as Saddam Hussein is ensured by the presence of American and British warships in the Persian Gulf, prevented the use of Anglo-American bases on their soil against the Taliban. The Saudis went as far as saying that "if the Americans attacked any other Muslim country" — meaning Iraq — after finding evidence linking that country to bin Laden, Saudi Arabia would side with that country. In other words, the 50 or so Islamic-majority countries proved en masse that, in the words of the Christian Arab writer Amin Ma'louf, now living in France, "Islam is a global tribe." No matter how criminal one of its members may have become, non-Muslims must not touch him.

Thus the longer-term future seems as gloomy as the next few years. While western leaders are genuine in their desire to prevent this crisis from expanding into a clash between their two worlds, Muslim leaders, tyrants to a man, may find it impossible not to pander to the worst instincts of their populations.

Furthermore, there seems no end in sight to the population explosion that, combined with a culture that glorifies violence and conquest, fuels the resentment of most Muslims against the prosperous West. The millions of young people who come onto the job market every year from Indonesia to Morocco have very little chance of their dreams being fulfilled, even if their governments were suddenly to become less corrupt and more competent. The young of the Muslim world, deprived of a decent education and realistic hope, will continue to be easy recruits for fiery preachers who still talk of Allah's miracle in "holding up the sky without pillars".

Under such circumstances, I see no alternative to the West having to cut its links with the world of Islam to the bare minimum and, in particular, beginning immediately to invest vast resources of cash and expertise to make itself independent of Middle Eastern oil. In the worst case, the old dividing line that ran roughly along the length of the Mediterranean and separated the world of the Saracen from that of the Crusader in the eleventh century may impose itself upon us once more. We must do everything we can to prevent that.