THIS autumn marks the 20th anniversary of Samuel Huntington's essay "The Clash of Civilisations". Arguing that in Europe the "velvet curtain of culture has replaced the iron curtain of ideology", Huntington went on to predict that the future driving force for international conflict would be culture and religion rather than geopolitics or economics.

For example, he said, the conflict along the fault line between Western and Islamic civilisations was likely to become more virulent, and we could expect continued battles between Muslims and neighbours.

The essay, and the book that followed, were treated with derision by many of the intellectual élite. The writer Fouad Ajami was one of the first to insist that Huntington had "underestimated the tenacity of modernity and secularism" in places where they had previously been absent. This expanding mindset would act as a preventative force against civilisational conflict. Yet, just eight years later, the optimism of these critics was put to the test by the carnage of 9/11.

There are problems, of course, with Huntington's thesis. Some civilisations are vast - "Western civilisation" envelops countries and whole continents. Some civilisations, such as the Islamic, are religiously defined, with Arab, Malay, or Turkic subdivisions; others, such as China, have old religious undertones. And although civilisations have certainly clashed over the past 20 years, almost as many clashes have occurred within them. The conflict between Sunni and Shia shows that single religions may have their own fault lines.

The Roman Catholic writer John L. Allen offered another perspective ("The War on Christians", The Spectator, 5 October). He quotes the secular International Society for Human Rights, which says that 80 per cent of all acts of religious conflict have been directed at Christians. The Study of Global Christianity at Wenham, Massachusetts, reports that this translates to an average of 100,000 Christians killed each year for the past decade.

Huntington was right, in that many of these are Christians who have suffered at the hands of Muslim militia. But he was wrong in identifying Christianity simply as a subset of Western civilisation. Christianity is a global movement of 2.3 billion adherents. The Christians who have been maimed or raped are not those in North America or Europe, targeted by competing "civilisations", but are indigenous in those civilisations themselves, sometimes speaking the same language and eating the same food.

Over the past 20 years, two-thirds of the Christian population of Iraq has gone - exiled, or killed. A survey by the Pew Forum, in the United States, suggests that, from 2006 to 2010, Christians faced some form of discrimination, either de jure or de facto, in 139 nations.

Mr Allen cites recent examples from Pakistan, Kenya, Nigeria, India, Burma, and Korea to reinforce this point. He insists, however, that this is not "limited to a clash of civilisations between Christianity and Islam". Hindu radicals were responsible for 500 deaths and 50,000 made homeless among Christians in Orissa. The 300,000 Christians who disappeared from North Korea, feared dead, were persecuted for refusing to join the cult around its founder, Kim Il Sung. Mr Allen's conclusion is: "In truth, Christians face a bewildering variety of threats, with no single enemy."

The debate over Huntington will continue, but a more urgent need is to address the human-rights violations and anti-Christian persecution across the world; vehement opposition to it has to be on the agenda of all civilisations.