On November 19 the arrival of "the new racism" was eagerly heralded on the cover of G2 - tricked out, for the occasion, to resemble some scabrous, illiterate hate-sheet of the 1930s (Julius Streicher's Der Stürmer, for example). Well, this is what's new about the new racism: it isn't racist. Ronan Bennett writhes and toils in the coarsest of category errors. The question before the house is not about race. It is about ideology.

When I was five or six years old, my father took me to meet a black man. To be more accurate, my father (at that point, incidentally, a communist and universalist) made a call on a visiting academic from, I think, Nigeria, and he brought me with him. "He's a black man," said my father on the way. "With a black face." We went there by bus, and my sensorium was entirely immersed in the savage joy of riding on the red doubledecker (upstairs, in the smoking section). "He'll be black. He'll have a black face." And I remember thinking, Whew, Dad's going on about this a bit, isn't he? On arrival, I entered the room - and there was the black man, who had a black face.

"You've got a black face!" I said, and burst out crying.

"Of course I have! I'm black!" he said, and burst out laughing.

And when my father comforted me, I already felt that I had failed to deserve his consolation.

That was in Swansea in the mid-1950s. I had never seen a black man before (not even on television: we had no television). And now I feel that this was the only serious deprivation of my childhood - the awful human colourlessness of South Wales, the dully flickering whites and grays, like a Pathe newsreel, like an ethnic Great Depression. In common with all novelists, I live for and am addicted to physical variety; and my one quarrel with the rainbow is that its spectrum isn't wide enough. I would like London to be full of upstanding Martians and Neptunians, of reputable citizens who came, originally, from Krypton and Tralfamadore. It makes me uneasy to quote myself, but I must use the weapon others use. Here are three gobbets from the Independent (January 2007):

"The form that Islamophobia is now taking - the harassment and worse of Muslim women in the street - disgusts me. It is mortifying to be part of a society in which a minority feels under threat."

"The difficulty has to do with the nature of national identity; and the American model is the one we ... should attempt to plagiarise. A Pakistani immigrant, in Boston, can say "I am an American", and all he is doing is stating the obvious. Can his equivalent, in Bradford, say the equivalent thing in the equivalent way? Britain needs to become what America has always been - an immigrant society. That is in any case our future."

"The best thing [about returning to the UK after a 30-month absence] has been to find myself living in what, despite its faults (despite a million ills), is an extraordinarily successful multiracial society. This is a beautiful idea, with a good chance of becoming a beautiful reality, too."

Can Ronan Bennett really be so hard-up for racists that he is reduced to excoriating the author of those lines? My observations were made in response to questions posed by the newspaper's readers, and they were sent in by email. So: somewhere between an interview and an essay. And can we hang on to that distinction for just a little while longer? What you say about something is never your last word on any subject. But what you write should aspire to be just that: your last word. To paraphrase and slightly adapt Vladimir Nabokov (Strong Opinions): I think like a genius, I write like a distinguished man of letters, I talk like an idiot.

Ronan Bennett thinks like an idiot. An extraterrestrial just off the ship, reading him, would assume that nothing unusual has happened since September 10, 2001 - except for a dismaying increase in what he (uselessly) blankets as "Islamophobia". My inflammatory remarks, made in a newspaper interview, inflamed no one at the time, because the time (August 2006) was also the context. August 2006, and the revelation of a third jihadist conspiracy, in the space of 13 months, to massacre a random sample of British citizens: in this case 3,000 people. The comments I made, in addition, were prefaced by the following: "There's a definite urge to say..." When Bennett wonders why I don't "recant", what does he expect me to do? Pretend that I didn't in fact experience this transient impulse (which was not racist but simply retaliatory)? Does he want - do you want - novelists to sound like politicians, or like the pious post-historical automata that Bennett and Eagleton claim to be? Do you want the voice of the individual, or the aggressive purity of the ideologue?

"Islamophobia is racist": this is Bennett's single contribution. But before he can clamber on to his Medusa's Raft, he first has to put it about that I make no distinction between Islam and Islamism: "[He] is talking about Islam, not Islamism, Muslims, not Islamists". All right. Here's another quote (from the essay of 2006 originally and hereafter entitled Terror and Boredom: The Dependent Mind):

"We can begin by saying, not only that we respect Muhammad, but that no serious person could fail to respect Muhammad - a unique and luminous historical being... Judged by the continuities he was able to set in motion, Muhammad has strong claims to being the most extraordinary man who ever lived... To repeat, we respect Islam - the donor of countless benefits to mankind ... But Islamism? No, we can hardly be asked to respect a creedal wave that calls for our own elimination ... Naturally we respect Islam. But we do not respect Islamism, just as we respect Muhammad and do not respect Muhammad Atta."

Now comes Bennett's dialectical leap. He writes that I am hostile to Islam on racial grounds - a self-evident absurdity. Consider what a vast project of antagonism he sets before me. Racial hatred directed at over a quarter of humanity; racial hatred directed at pretty well every ethnicity on earth. (And what does he imagine I make of someone like David Myatt, the neo-Nazi and Holocaust-denier who now calls himself Abdul-Aziz ibn Myatt? Do I crinkle my nose in indulgence, because this fierce jihadist is white?) It ought to be a rule of the discourse, of any discourse, that one novelist should give another novelist the basic credit of not being a maniac.

I must have seen Bennett coming when, in April of this year, I reviewed Mark Steyn's alarmist but broadly pertinent book, America Alone (and here I quote myself for the last time):

"Any acknowledgment of the fear of being out-bred inevitably reminds us of eugenics and forced sterilisation and the like; and many good modern westerners, reading Mr Steyn, will feel the warm glow of righteousness that normally precedes an accusation of 'racism'."

But it's not about race. It's about ideology.

If every inhabitant of a liberal democracy believes in liberal democracy, then it doesn't matter what creed or colour they are. If, on the other hand, some of them believe in Sharia and the Caliphate (and believe, too, that slaughtering the attendees of ladies' night at the Tiger Tiger discotheque is a good way of bringing that about), the numbers start to matter.

When I interviewed Tony Blair earlier this year I asked him if continental demographics had yet become "a European conversation". He said: "It's a subterranean conversation." And we know what that means. The ethos of relativism finds the demographic question so saturated in revulsions that it is rendered undiscussable. As a multiculturist ideologue, Bennett cannot engage with the fact that a) the indigenous populations of Spain and Italy are due to halve every 35 years, and b) this entails certain consequences. He reaches, like a flustered commissar, for the polemical violence of "white supremacism"; he reaches for the race card - that silver hand-grenade of the virtuous.

Terry Eagleton started this ragged furore, with an attack in the Guardian that contained three factual errors in its first sentence [one of these, concerning the publication date of Amis's essay, was the Guardian's mistake, not Eagleton's]. Bennett, who is rather more scrupulous, now comes in at the scavenger end of it. Anyway, it is a miserable chore even to imagine these writers at work, dourly assembling their diatribes, hopscotching and cherrypicking from a press interview here, a TV interview there, an essay, a short story, some gout of alphabet soup in the Daily Mail, distorting this, suppressing that, and fudging the other. They are not interested in arguments and ideas, but in staking out "positions", in sending "signals", and in flirtatiously seeking the approval of the likeminded. This isn't the first time I have been accused of racism ("anti-Semitism" in 1991 for the novel Time's Arrow); and it is a calumny like no other. It paints a cross on your front door.

Let us as close as Bennett closes. It is a little epiphany, a little poem, of pharisaical self-congratulation: Amis got away with it. He got away with as odious an outburst of racist sentiment as any public figure has made in this country for a very long time. Shame on him for saying it, and shame on us for tolerating it.

Well, shame on me, right enough, and shame on everyone else - but not on you, Mr Bennett. Read that last sentence again. You didn't tolerate it, did you? No, you come out of this uncommonly well. Your disgrace isn't social; your disgrace is moral, intellectual and artistic - but no one's going to bother you about that. I will just say, in parting, that the ideology you appease (let's follow Francis Fukuyama and call it jihadism) is irrationalist, misogynist, homophobic, inquisitional, totalitarian and imperialist. And it isn't merely "racist". It is genocidal.