Isis will never be defeated until Western societies stand up for their own values
The Duke of Wellington famously said that the Battle of Waterloo was won on the playing-fields of Eton: and if that is the case, then the advance of the Islamic State was begun in the nice, tolerant, liberal academies of Britain and other parts of western Europe.
There are now more British Muslims fighting for the Caliphate - the globalised rule of fundamentalist Islam - than there are Muslims in the British Army. These Jihadists attended pleasant, multicultural English schools and enlightened English groves of academe such as King's College and the London School of Economics.
Why, oh why, goes the bewildered cry - from the prime minister to the former Archbishop of Canterbury - do these young people rush off from Britain (and some from Ireland) to join in a hateful conflict that beheads good men like the journalist James Foley and wages war against Syrian and Iraqi Christians and Yazidis?
Many remedies are now being proposed to halt the "radicalisation" of young Muslims and there is much huffing and puffing about confiscating their passports (probably illegal under European protocols), tooling up more military hardware, or making friends with odious dictators such as Bashar al-Assad because he, too, would suppress terrorists.
But most of these schemes for a fightback against Isis and its ilk fail to recognise a basic truth: that wars are not won just by military hardware or political re-arrangements. They are won by ideas.
They are won by men and women who have convictions and values which give them the impetus to pursue victory.
Everything the Americans could throw at the conflict in Vietnam in the 1960s and 1970s - which was, indeed, a war against the predominance of a Communist regime - came to naught. Despite superpower military strength, America retreated in a humiliating defeat, and popular culture now considers that America "lost" that war.
In another context, however, the defeat of Communism was eventually achieved - not by bombs and guns, but by values and ideas. Three individuals with unshakeable beliefs in their own values brought down the Iron Curtain: Ronald Reagan, Margaret Thatcher and Pope John Paul II. What united these leaders was that they believed, firmly, in their own convictions.
To wage war against a values-system, you have to hold, to believe in, and to affirm with confidence, a values-system. But today this is, largely, what the West lacks in facing a phenomenon like fundamentalist Islam. Western liberal societies have preached - and practiced - the doctrine of "multiculturalism" since the 1980s: but Kim Howells, one of Tony Blair's former ministers, spoke with insight over the weekend when he said in response to current events: "We're paying a bitter price for multiculturalism."
Because, in reality, there is no such thing as "multi-culturalism". Wherever there is a clash of cultures, one culture eventually emerges as the dominant one, and the weaker one succumbs.
Nature abhors a vacuum. If you don't believe in your own cultural traditions, and if you are not ready to defend them, a stronger culture will take its place. Since the 1980s, deference to "multiculturalism" has meant in British - and, increasingly, in Irish - society the abolition of Christian, and Judeo-Christian, symbols and customs.
Most recently, the budget hotel chain Travelodge has banned the placement of the Bible in hotel rooms - a tradition carried out by the Gideons for more than a century - on the grounds that it doesn't respect "diversity and equality". A small thing, but mark my words: where the Bible is banned, the Koran will soon take its place.
The young people from Western societies who have rushed off to join ISIS have, for the most part, been brought up in an ambience where there was careful deference to multiculturalism in general, and to Islam in particular.
I saw it in the London schools from the 1980s on, when the mainly left-wing local authorities started to ban Nativity plays, as insufficiently reflecting "multiculturalism". (The Irish Army is now going down the same path by banning the old Irish custom of the Christmas crib.) Yet I also observed that believing Muslims were more likely to be contemptuous of, rather than grateful to, the multicultural enforcers.
These young men - and the Jihadists are mostly male - didn't want "multiculturalism": they wanted commitment and conviction and a cause they believed was noble and transcendent. And one which demanded sacrifice.
There's nothing wrong with tolerance and a universalist outlook: these are good things. But if a host society is craven and defeatist about its own history and traditions, then it is asking for trouble. Western societies must uphold the achievements based on our values, and do so with fortitude. If we constantly disparage Christian heritage, others will assume that it is weak and moribund, and they will despise it too.
Isis will not be defeated by drones, military action or even politics alone, but by ideas and leaders who really and truly believe in their own values and traditions. After James Foley was beheaded, it was triumphantly announced that: "The sword is mightier than the pen".
But ideas, and the conviction to carry them, are still stronger than all else.