September 11 is burned on the memory of mankind. For the present generation, the images of the planes flying into crowded skyscrapers or the frightful pictures of people leaping to their deaths will remain vivid and deeply disturbing.

But in the future, the history books may rate 2001 alongside 1066, or 11.9.01 beside 3.9.39, as dates when the world changed. One year on, we can make a clearer assessment of why the world will never be the same again and why the long-term effects of September 11, 2001, will affect our grandchildren and their children.

One piece of evidence is the conference, on the September 5-6 this year, organised by the US State department, on "Why do they hate us?" Clearly US diplomats and politicians are trying to discern why there is so much antipathy towards America. Such a conference would have seemed irrelevant before September 11.

I saw the immediate American reaction when I visited Atlanta soon after the terrorist atrocities. Stars and Stripes flew in every garden and "God bless America" was a slogan on every corner. But a few weeks later, I saw another side of American reaction when I publicly questioned the conditions under which Afghan suspects were being held. My e-mail was full of vitriolic messages from Americans. They seemed unaware of the fact that British people were a significant proportion of those killed in the terrorist attacks. The anger, perhaps understandable at the time, was motivated by the thought that the greatest nation on earth should not be open to either sympathy or criticism from anyone else.

So the cry "Why do they hate us so much?" sprang from incredulity that a significant number of people in the world questioned the American dream and the effect it has on other nations. Terrorism had made that plain, and awakened in the American consciousness that US economic, political and military assumptions could no longer be universally accepted.

In the following months, American pride was to take further blows. The collapse of Enron raised questions about the very institutions which provided livelihood for thousands - both in terms of employment and investment. President Bush's refusal to participate with the rest of the world in tackling serious environmental issues suggested a superior isolationist policy.

The US military strategy regarding Iraq has fuelled criticism of American engagement based solely on military power. Fears have surfaced about internal attacks using chemical weapons.

So, since September 11, 2001, the world has changed. The US finds itself infected by distrust within and without. Its complacency has taken a huge blow and even thinking Americans have begun to question whether American policies are right in the context of obligations to the civilised world.

Of course, the US has no real competition as the most powerful nation in economic and military terms. The intelligence and basic goodness of the majority of American people will no doubt help them to bounce back.

But the September 11 attacks have sown the seeds of doubt about the vulnerability of the US. That vulnerability has been exposed by a relatively small and weak band of extremists. Their motivation is a powerful mixture of religious fundamentalism and political fanaticism. However much we despise their strategies, it is a mistake to underestimate their potential for creating disorder and destabilisation in the world. That is their intention. They need to be stopped.

But how we intervene to prevent terrorism has raised questions about the assumptions that military power is the answer. The use of military force is to be questioned, not only on moral grounds but also on practical outcomes.

All the might of the US and its allies has not obliterated a gang of bandits hiding in the mountains and spreading through networks across the world.

It becomes, therefore, a battle of minds, moralities and ideals on the three fronts of politics, economics and religion. September 11 may ultimately have inaugurated a new way of doing international politics; fresh approaches to matching economic growth to social justice; a completely new understanding that, even in the 21st Century, religion remains a powerful motivation for good and for evil.

So the new questions we are asking involve rediscovery of the good (if uncomfortable) things religion has to offer to the world and eradicating its worst forms of blind fanaticism.

No doubt, the majority of Muslims in the world are good people but they need to be warned that religion, of all things, cannot be perpetrated by atrocity. Christians and Jews need to be heard for their highest ideals, but asked to look again at a God for whom justice and peace must control the lust for economic growth and supremacy. And politicians must learn to listen, to shed their arrogance and confess that politics must be undergirded by long-term moral principles, unclouded by the kind of passing populism which has an eye to the next election.

Without this new approach we are lost. Barbarism will take over from civilisation.

And in our own little ways we all have a part to play by our attitudes to all religions, by our participation in the re-shaping of politics and by recognising that an economics of sharing must overtake hoarding and greedy competition. For since September 11, we know the world is one and in danger. The questions belong to all mankind. To make the wrong choices we now know will lead, imminently, to disaster.

A new age has begun. How long it lasts depends on us.