I HAVE never watched a video of a beheading, but I thought last week that I would have to start. To type those words makes me feel as if I am beginning a science-fiction story, but, as William Gibson says, the future is here already; it's just not evenly distributed. And the future involves sharp knives in the desert, filmed in high resolution, so that we seem to be watching an out-take from the first Star Wars film while a man in a penitential garment kneels and says his piece to camera.

It was a lesson in why the Stalinist show-trials worked, and why the Inquisition did, too. The spectacle of humiliation is horribly compelling. But there is a twist to this. The ghastly compulsion exercised by the spectacle of someone lying as sincerely as he possibly can becomes electrifying when he refuses to lie.

Watching James Foley, I understood how powerful a witness an unresisting martyrdom by public execution must have been. The victims were not then killed just for being Christians (or Protestants, or papists). They were killed because they stood when they were meant to kneel. They would not worship. They refused the speech that their captors would have put in their mouths. They would not abase themselves to be reconciled with their killers.

But Foley spoke. His speech ended with the words: "I am ashamed to be an American." They killed him anyway. That was not shown on the clip that I watched, and may not be on any of the ones circulating, to judge from later reports, which suggest that the video had been edited so that the hooded braggart who held a knife to his throat was not the man who actually killed him.

So, in some sense, I still haven't watched a video of a beheading, and I am very grateful for this. But the Foley video, simply considered as an act of propaganda, makes clear, as nothing else could, one of the things that makes young men into Jihadis. It is the fantasy of power.

Mona Siddiqui, in The Observer, wrote: "Many young men see war as a drug, all powerful and mindblowing, with the thrill of donning a uniform and carrying guns. But we are no nearer understanding the appeal of a nihilistic rhetoric among middle-class, educated young men other than it may be a way of unleashing all kinds of psychological frustrations.

"This is not a failure of integration; there is a deeper malaise than that tapping into a sense of emotional unfulfilment when you have everything."

This is the most profound and least windy response I read to the atrocity. To humiliate and slaughter your enemies when you are feeling powerless and outcast speaks to something deep inside an adolescent male. Nor do you have to be actually powerless and outcast to dream that way. In fact, that may make it harder, since you have less time to brood on your grievances.

It is a shocking and possibly absurd thing to confess, but, as a privileged misfit at rather grand schools, I would have loved at the time to make some of my teachers and school-mates die in a spew of self-hatred and self-abnegation.

There was quite a lot of discussion, not least in The Times, of whether the "Beatle", "Jihadi John", who played the part of Foley's killer in the video, had actually performed the act, or whether he had been chosen as an actor because his accent was so recognisably London. To portray one Westerner beheading another for the sake of Islam is a masterly piece of propaganda, even if every part of it is untrue. It certainly captured the attention of the Western media: I would not be surprised if more had not been written about the death of this one journalist than about all the suffering of Iraqi Christians this year.

AND so from real horror to the largely fantasised variety. The American lunatic magazine World Net Daily (WND) had a piece on Vicky Beeching which I found illuminating. "An evangelical Christian worship singer who has been urging churches to change their doctrine on homosexual behavior since announcing she is a lesbian is at the forefront of a coming tidal wave of 'infiltration' of the church by promoters of the 'gay' agenda, contends evangelical attorney, evangelist and activist Scott Lively."

Lively was the man whom Channel 4 put up against Beeching in a debate, presumably as a way of discrediting all her opponents. He is widely blamed for inciting the Ugandan "Kill the Gays" laws, but WND reminds me that he is also the author of The Pink Swastika, an alternative history of the Nazi party. "From the party's founding in a homosexual bar, 'The Pink Swastika' introduces the reader to all the household names of Nazism - from Goebbels to Goering and Himmler to Hess - and their secrets of sexual perversion, one of the driving forces of their genocidal sadism."

This explains why the worst Nazis were known as camp commandants.