Muthana like so many others is not — or is not just — the mindless murderer of the tabloids' imagination. His religious ideology is genuine. Nor is he a voice of the oppressed. He once gave every appearance of being a fine young man. His father described him as "quiet and well-educated". Four universities offered him a place to study medicine. You could not find a less likely example of the left-wing fantasy of the misguided extremist driven to violence by the "root causes" of poverty, disenfranchisement and marginalisation.

I and, I suspect, the government will ask different questions about his career and the careers of his fellow killers. When in his journey towards barbarism did he hear liberal arguments against radical Islam? Where would he have encountered a fightback against men who are so sexist that they rape and enslave women? So sectarian that they condemn heretics to death because they do not share their version of Islam? So homophobic, paedophile, anti-democratic, anti-Semitic, sectarian, vindictive and violent that they might have stepped out of a liberal nightmare?

Hundreds, maybe thousands, of young British citizens are committing crimes against humanity. The politicians are responding with their usual crackdowns — and I turn queasy when I imagine what new laws and trouble in the streets there will be when and if Islamic State recruits bring their war home.

Culture matters as much as laws, however. It may not have the power to arrest and punish, but it is more persistent and ubiquitous. It seeps into the corners the police can never reach. For the young in particular, what their friends argue against and deride will have more effect on them than the lectures of government ministers. And the truth is Britain, Europe and the United States do not have an anti-fascist culture.

There are anti-Islamic and racist subcultures everywhere. From the British National Party to the tabloids via UKIP, prejudice against Muslims because they are Muslims flourishes. The Left will condemn it, and rightly so. But it will not as a general rule stand with liberal Muslims and ex-Muslims fighting against their own religious Right. In Britain today friends of mine live like dissidents in a dictatorship. They meet in secret. They vet new arrivals to ensure they are not spies. They are ex-Muslims living in a supposedly free country who fear their enemies will damn them as apostates and kill them. How extraordinary that they must hide their true beliefs from all but intimate friends for fear of the consequences. And how shameful that they have no anti-fascist Left worthy of the name to defend them.

The Left will fight the white far-Right. In Britain, groups like Hope not Hate organise protests against UKIP. Think what you will about UKIP — and I think nothing but ill about them — but it is not actually recommending the rape of enslaved women. On Twitter and in the universities there are constant demands to ban and punish those who show the smallest disrespect to women — scientists who wear racy shirts, men who argue against abortion, pop singers who promote a rape culture, and pick-up artists who instruct men on seduction techniques. But with honourable exceptions, leftists will not argue against armed misogyny. On the contrary, they will ban those who try to take it on.

A few weeks ago, the Lawyers' Secular Society was due to present a report to law students at the University of West London on the Islamic supremacists who have spoken at British campuses in 2014. The university banned the society from holding its meeting. (It would produce "bad publicity", apparently.) In other words, while extremist preachers stalked the campuses, students who wanted to argue against them were thrown out.