No matter that they act like senile 12-year-olds on the Today programme website - smoking illegal fags to look tough and cool. No matter that Amis coins truly abominable terms like 'the age of horrorism' and when criticised tells people to 'fuck off'. Surely we all chuckle at the strenuous ennui of his salon drawl. Didn't he once accidentally sneer his face off? His 'insight' about Mohammed Atta involved pretending the hijacker was constipated for six months - brilliantly smuggling into our subconscious that idea that Atta was 'full of shit'. He abandoned his satire on terrorism in which a Muslim unleashes mass rape on America because 'faced with Islamism, even satire withers and dies', not because his idea was obviously rubbish.

Despite his manifest absurdity (he called the World Trade Centre attacks 'edificide' and the towers' destruction an 'apocollapse'), people take him seriously and if they do then we must.

Last week Amis was called a racist. I saw him speak at the ICA last month. Was his negativity about Islam technically racist? I don't know. What I can tell you is that Martin Amis is the new Abu Hamza.

To recap, Amis was called a racist because he said Muslims were backward, violent, homophobic, paranoid, boring, retarded and stupid. Hitchens said no, he's conducting a 'thought experiment'.

Now Amis should be allowed to wonder aloud about anything. He can suggest Muslims should 'experience painful discrimination until they get tough with their children' if he likes. Thought experiments are fine. But if he bundles his thoughts on Islam together and iterates them one after the other as he did when I saw him, he displays not unguarded musing but the forging of an incoherent creed of hate. It goes roughly like this: 9/11 was horrific, its driving ideology was totalitarian, the totalitarians were Muslims, all Muslims follow a book they believe to be the immutable word of God, I don't believe that, therefore all Muslims are idiots, and basically bastards. Idiot bastards moping around the Middle East in a paranoid funk just cos they lost their empire, and what a rubbish empire it was, too, by the way. Now, what is your balanced view of these primitive wife-beating idiotic bastards?

Like Hamza, Amis could only make his nonsense stand up with mock erudition, vitriol and decontextualised quotes from the Koran. To risk a familiar example, it won't do for Amis (or Hamza) to state flatly that the Koran exhorts Muslims to kill Jews without even asking whether this means all Jews or some particular group of Jews with whom the Muslims were fighting in the seventh century, or indeed, whether there are other verses that modify the message by deploring killing of any kind, or describing how 'people of the book [Christians and Jews] shall have nothing to fear or regret'.

I claim no great knowledge on this subject - level-three SATs perhaps - but Amis couldn't pass the test for morning playgroup. If my Shetland pony looks like a high-horse it's only because Amis is trotting round the paddock on a chihuahua.

So how does Amis manage to move from condemning the horrors of suicide bombings to pouring scorn on anyone who can believe in paradise - effectively all Muslims? He muddles his terms. Even Hitchens concedes Amis wrongly conflates Islamism with Islam. By fudging, Amis adds the weight of his reaction against terrorism to his contempt for Muslims in general. Take 'Islamism'. What does it actually mean?

For many it means 'political Islam'. Amis calls it a 'murderous ideology', equating it with terrorism. Now look at the following statement: 'The terrorist killings in New York, Madrid and London were wrong. They were indiscriminate, un-Islamic and based on ideas abstracted to the point of insanity.' I was firmly told this by an ex-Mujahideen who fought in Afghanistan 20 years ago. He was an Islamist. I strongly doubt he was murderous.

These concepts are more complex than Amis would have us believe. This lack of clarity allows him to group Muslims who stop teenagers shooting one another with a man who cheerfully saws the heads off Jews.

It's not easy. Even ex-Islamists seem confused. Ed Husain - whose Hizb ut-Tahrir memoir The Islamist made him the summer's top ram-raid sound-biter - condemns Islamism as 'totalitarian' but later allows for 'moderate Islamists'. What sort of braincrash is a 'moderate totalitarian'? I doubt it could even walk.

These distinctions matter because the way out of this mess (and it is a mess, fuelled by ignorance, stupidity, prejudice and weapons) is to clarify and discriminate rather than hurl abuse at anything that goes near a mosque.

I doubt many Muslims can be bothered with Amis. But he nurtures in his audience a corrosive prejudice against people they've never bothered to meet. It is culturally dim for us to form confident opinions about people based upon how they look and what we've heard they think. It is also against our interests. Nonsense abounds on the causes of terrorism but it is hard to argue that alienation doesn't channel potential foot soldiers towards radicalisation. As one solitary Muslim asked him at the ICA, 'Why such contempt for Muslims?' Amis must have known something was up because he dropped his drawl and called the man 'sir'. But he could hardly unspeak his views. And those views are certainly alienating.

With ignorance on his side, Amis can stare east through the salon window and convince us of a single advancing horde. He's clever. He might put it brilliantly. He might call it a 'Meccalanche' or an 'Attaclysm'. But when he speaks, think 'Hamza'.

· Chris Morris is making a comedy about jihadis for Channel 4

· This article was amended on Friday November 30 2007.

· This article was amended on Sunday December 9 2007. Homophone call: '... Amis can stare east through the salon window and convince us of a single advancing hoard.' This has been corrected.