For years we in the West have been looking for a new Evil Empire to fill the gap left when Russia - a genuine threat - retired from the job and deprived us of an enemy. What were all those spies to do? How could we justify those missiles and bombs? What should we be scared of now?
At one stage we were reduced to pretending that Panama's General Noriega was a menace to our way of life. Then it was Slobodan Milosevic. Finally, we inflated the piffling Saddam Hussein into a looming Hitler.
Now the same experts think they have found something to be afraid of in Iran. It is tempting to believe them. This is the land of the glowering ayatollahs, the book-burning mobs, the fatwas of death and the black chador. And Iran has just become even more frightening because in its secret vaults Islamic scientists are fumbling with atoms and testing long-range rockets.
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Changing tastes: An Iranian mother and her daughters enjoy ice creams
Holiday snaps: Friends take photos of each other on a beach
Such is our terror of this mysterious land that Navy bluejackets and Royal Marines seem to have thought they were in the hands of cannibal dervishes when they were captured by them, quailing at the thought of rape, torture and death. Even now, having been subtly humiliated instead of butchered, they do not seem to have grasped that things might not be as they seem. Nor have many of us.
When I told my friends and family I was going to Tehran, they looked at me as if I were taking a short break in Mordor, and expected that the next time they saw me I would be being paraded by Revolutionary Guards after confessing to espionage, and then publicly hanged from a large crane at a busy traffic intersection.
Well, not quite. The people of Iran are probably the most pro-Western in the world, though that will not stop them fighting like hell if we are foolish enough to attack them. Not that they will do so with nuclear weapons any time soon. Iran is rather bad at grand projects. Its sole nuclear power station has never produced a watt of electricity in more than three decades, the capital's TV tower is unfinished after 20 years of work and Tehran's airport took 30 years to build.
By bringing this information back to you I expect to annoy the frowning mullahs, who want their people to fear us as much as George W. Bush and Anthony Blair want us to fear Iran. That is why they constantly tease us about their inadequate nuclear programme. They long for our rage and threats.
Again and again, Iranians told me Western hostility was the main force that could push them into the arms of a regime they did not much like. The last thing the ayatollahs need is for the peoples of Europe and America to know much about their country and its people, or to realise the truth - that Iran is our natural ally in the Middle East, a European civilisation trapped by history and geography in the midst of Arabia. It does not belong there, culturally or religiously.
We treat Turkey like a brother, when it is a militant Islamic state kept secular only by a disguised military dictatorship. And we treat Iran like a pariah, when it's a largely secular nation kept Islamic only by an ageing and discredited, but open, despotism.
In the past ten days I have travelled across beautiful, hospitable Persia and talked to many of its people, unsupervised, unmonitored and unofficially. I have been inside private homes and found out what Iranian people think and why. I have met citizens who voted for President Mahmoud Ahmadinejad, citizens who now wish they hadn't and those who think he is a sick joke.
I have sat among hot-eyed zealots at Friday prayers in Tehran as they chanted 'Death to England'. I have seen the melodramatic anti-aircraft defences round the nuclear plant at Natanz. I have met supporters of the regime and endangered, persecuted dissenters, as well as plenty in between. I am under no illusions about how barbaric the government can be to those who challenge it openly in the Press or other public forums. But I think its power is waning, and can be kept alive only if we are fool enough to fall for the propaganda of the people who brought us the Iraq War.
I have tried to understand the sweet, sad mystery of Iran's unique brand of Islam, quite unlike the hard, aggressive faith found in the Arab lands. I have touched the silver bars of the holiest shrine in the country, as the pious crowds thronged around it, many crying out in ecstasy that they have reached this sacred place. I suspect these scenes are the closest I shall come to what English pilgrims to Canterbury must once have known.
I have heard the hundredfold 'thwack' as prayer carpets were unrolled across enormous, majestic courtyards and watched the faithful at their evening devotions beneath gold domes and among some of the loveliest architecture on the planet. I have also talked to those who enjoy the illicit thrill of drinking whisky in an Islamic republic whose soldiers still spend hours smashing smuggled cargoes of alcohol. I have observed the cunning efforts of Iran's women to subvert and mock the ridiculous dress codes forced on them by silly old men. I have seen how many others choose to follow rules of modesty they personally believe in.
I have been told unprintably rude jokes about the late Ayatollah Khomeini. And I have been kissed on both cheeks by a hairy mullah in the holy city of Qom.
Let me begin in Tehran, Iran's colossal, ugly and charming capital city, which contains two wholly different nations within its ever-expanding boundaries. This is a very young city in a very youthful country. About 40 per cent of Iran's 70million people are 15 years old or younger, and in Tehran the concentration of the young is even greater.
Grinding along its clogged, modern streets where buildings are the colour of porridge or a sort of dirty custard-yellow, you see plenty of evidence of the horrible, murderous revolution that shocked the world in 1979. Portraits of Khomeini and of other religious leaders are everywhere. So are anti-American murals - the most striking is a US flag in which the stripes are the slipstreams of falling bombs and the stars are replaced by skulls.
On the walls of the long-deserted US Embassy, site of the kidnap of dozens of diplomats, slogans in English and Persian still promise to inflict a great defeat on America. Perhaps that promise has now been fulfilled in Iraq, a few hundred miles away, where American arms have suffered their greatest catastrophe since Vietnam - though the White House does not seem to know it yet.
But these things are old, flaking, faded and largely ignored by the people. They have other things on their minds - mainly private life.
In a bustling restaurant in north Tehran, where Iran's wealthy middle classes live, it is obvious that Islamic dress has been forced on the many women present and that they are determined to let everyone know it is not their choice. Personally, I found Tehran much less oppressively Islamic than Kensington High Street in London, where an ever-growing number of women voluntarily go about in black shrouds, masks and veils.
This is not some medieval theocracy where females are hidden away or forced to do the will of their menfolk. Men and women sit in animated mixed groups at the lunch tables, conversing as equals. Headscarves are worn. It is still the absolute law. But they are worn in such a way as to make a fool of that law. They are pushed back as far as they can go without actually falling off, held in place by no more than a blast of hairspray, revealing the front parts of elaborate and often vertical hairstyles - frequently blonde.
In a park by a lake, some teenage girls are splashing each other. Incredibly, several of them have illegally taken off their headscarves. Even more incredibly, their teachers pretend not to notice. This would have been unthinkable a year ago. What unthinkable things will be happening a year hence?
Everyone knows next month there will be the annual ritual crackdown, when the police will reprimand thousands of women for defying the official code. And everyone knows that, once it is over, scarves will creep back a little further and heels will get a little higher.
On the streets the women walk and stand like Parisians. Somehow, with a belt here and an adjustment there, they manage to make the modest 'manteau' jackets look chic. They laugh and chatter. The days when public laughter was a criminal offence are long gone.
About one in 50 seems to have had recent plastic surgery on her nose. They wear their bandages with pride and some even stick plaster on their faces to pretend that they have undergone this subversive surgery.
The desire among lovely Persian women to look like Snow White is strange but it is a direct reaction to authority's attempts to make them look like bats and crows.
The fashionable cafes are full of painted, un-Islamic butterflies, sipping milkshakes or coffee. The upstairs rooms are reserved - by common consent - for couples to meet away from the intrusive eyes of their families.
In the evenings, cinemas are popular places for some mild canoodling, though it is unlikely to go further than a Fifties-style kiss. But there is plenty of extramarital and illicit sex in Iran, some of it licensed by the Islamic authorities who permit highly dubious 'temporary marriages'. Among the rich, operations for 'revirginisation' are quite common before marriage, and contraceptives, once prohibited, are now freely on sale. Prostitutes patrol the night streets. I point this out not because I am specially glad about it, but to show how morals enforced from on high will fail if they do not have real popular support.
But travel in the smooth, modern metro down to poor south Tehran and you will find many more black veils and chadors, and many more beards and ringed fingers, the usual signs of serious Islam and support for the regime. For it is the poor who have largely benefited from the revolution, which gave them state jobs and good schools.
Even here, things are not quite what they seem. My guide in this part of the city was Reza, who is now unemployed thanks to the mullahs' mismanagement of what ought to be a fabulously rich oil and gas economy. Reza recalls wryly: 'When I was four, Ayatollah Khomeini came to my school and blessed me. It's been downhill ever since - everything just gets worse. I've even gone prematurely bald where the old man put his hand on my head.'
In his part of town, there is often more fervour for football than for Islam.
Reza cannot hide his distaste when we go together to the great shrine to Khomeini, a few miles out of the city. This is a startlingly shabby place - and far from busy.
Its only charm is that the Ayatollah apparently willed that it should be a place of relaxation, so small children are allowed to run around and even play football close to the old man's tomb. On the motorway that leads to it, speed cameras alternate with signboards bearing quotations from the Koran.
On the anniversary of the Ayatollah's death, great crowds gather round the shrine in a strange celebration - half holiday, half memorial service. Stallholders sell mementoes and you might think they are keen on the Ayatollah's memory. But an Iranian-American friend recalls how he once tried to buy some Khomeini clocks to take home.
The salesman became suspicious. 'You're American, aren't you?' he asked the returning exile. 'Yes, I am,' the Iranian-American replied. 'What of it?' He thought the merchant was an admirer of the one-time supreme ruler and expected to be upbraided for being irreverent. But no. The clock-seller asked him: 'Then why on earth do you want to buy so many pictures of this ****hole?' Both exploded in relieved laughter.
Things are quite different at another nearby shrine, a shocking, city-sized cemetery for the young men who died in the terrible war with Saddam Hussein's Iraq. Each shaded tomb is decorated with a touching portrait of a very young man (some of the volunteers who marched into minefields or poison gas were as young as 11).
Suddenly Reza is not cynical. He shows me a grave that is said to be always wet (with tears?) and to smell permanently of rosewater. I think Reza wishes to believe in this miracle, even if he couldn't give a dried apricot for the rest of the official myths.
This war, which most Iranians regard as at least partly the doing of the West, ended in 1988. It is shamelessly used by the regime to create a sort of unity between the revolutionary government and the people.
It cannot last for ever. This year, for the first time, a comedy film was made about the war - reverence is beginning to fade. And so is the revolution's claim to have made life better, which is untrue for so many.
People are encouraged to visit the Shah's old palace, with its vulgar chandeliers, decaying tennis courts and enormous bedrooms, so that they can look on his opulent living quarters and rejoice that he was brought down. The Khomeini state has wittily sawn down a large statue of the monarch that used to stand here, leaving only his boots behind.
But people such as Reza have the wrong reaction when they come here. They walk around muttering that the Shah cannot have been that bad and become madly nostalgic for his reign, which was, in fact, notorious for corruption, secret-police savagery and wild incompetence.
The more the Islamic Republic tells them to loathe the Shah or America, the more they yearn to have the Shah back, and to live in America. In this country, America is probably more popular, even now, than in any other country on the planet.
Some people here, the Westernised intellectuals, have always despised a regime they see as backward and stupid. It is gospel among them that Khomeini was not specially clever. They refer scornfully to the regime's supporters - usually poor state employees or tradesmen - as 'Hizbollah'. Women who wish to join the West's drive for sexual equality also loathe the state and are loathed back. One woman I met had been arrested for her feminist views and is now facing trial. Her likely fate is a suspended prison sentence, which will be imposed if she steps out of line again.
But such people are always dissenters. To seek a more representative view, I took the clean, comfortable sleeper train 500 miles east to the shrine city of Mashhad, near the Afghan border, where I met many devout but open-minded and tolerant Iranians.
In some houses, the women stayed covered at all times and I could not even shake hands with them, bowing instead. In others, they dressed and acted like Westerners. It was clear that public opinion exists and matters here. I asked about the gruesome public hangings. My neighbour at the dinner table explained: 'At the beginning of the revolution these sorts of things, public hangings and floggings and the amputation of limbs, were common. But people didn't like them. They do sometimes hang mass killers or child molesters but if they announced the public hanging of an ordinary murderer, people would stay away to show their disapproval.'
Remember, this is a country that does have elections and those elections don't always go according to plan, despite ruthless official rigging. I asked those present if they had supported Ahmadinejad in the presidential poll. All hands but one went up. Would they do so again? No hands went up. By the way, the women dominated this conversation.
'We were hoping he would be different,' one said in justification. This kind of hope that something or someone will turn up is at the heart of Iran's Shia Islam, a religion of mourning and loss, whose adherents still feel woe over the defeat and murder of the three great Imams, Ali, Hossein and Reza.
These martyrdoms took place 1,300 years ago but are still grieved over, especially at the shrine in Mashhad where Reza's tomb lies. The real zealots mark this each year by beating themselves bloody with chains and slashing their scalps with swords. It is rumoured that people die at these events.
In a belief rather like the ancient British one that King Arthur will one day come back and save his people, Shias constantly await the return of the 'hidden Imam', who disappeared in 878 AD, and may reappear at any time, with Jesus at his side, to restore peace and goodness to the world. I know how this sounds in cold print, but even the modest 39 Articles of the Church of England look pretty extravagant when seen from the outside.
It would be hard for anyone to see the devotion of the pilgrims at Mashhad and not come away respecting the force of this faith, which is a living, normal thing among Iranians, as natural a part of their lives as the low passions of football and the Lottery are in ours. Who is to say they do not have the better part of the bargain? I have never been anywhere with such a sense of generous hospitality and consideration to strangers.
At the evening prayers, the sense of deep human emotion is electric. But it is important to realise Sunni Islam, the great majority of the Muslim world, regards Shia Islam as a serious, idolatrous heresy, much as Ian Paisley regards the Pope and all his works.
The austere brand of Islam favoured in Saudi Arabia is specially displeased by the Shia love of relics and glitter. When Iranian Shias go to Mecca, they are said to be treated with cold hostility. The only Shia beloved in the Sunni world is President Ahmadinejad, whose noisy, disreputable hostility to Israel and whose support for Holocaust denial has made him the taxi-drivers' favourite in every Sunni Muslim country from Indonesia to Morocco.
Which brings me to Friday prayers in Tehran, the weekly festival of loathing for the West that takes place in a hangar-like building in the university. Many of the thousands who attend are bussed in, and one of them, a soldier in uniform, confessed to a friend of mine that if he didn't bellow 'Death to America!' at the appropriate moment he wouldn't eat that day. A middle-ranking mullah presides, starting with a sermon on family values, and then moving on to political matters.
His message is interesting. Shia and Sunni Muslims, he urges, must forget their differences. Wicked England has been seeking to divide the two branches of Islam for centuries. There is a general belief that British spies are behind everything in Iran. It sounds funny, but it isn't. It dates partly from the 19th Century when, with guile and bribes, British agents controlled the south of the country, hoping to keep the western borders of the Indian Empire safe.
But more recently, it results from our involvement in a 1953 coup against Iran's most beloved modern leader, Mohammed Mossadeq. This cynical and short-sighted action was designed to stop Iran getting a bigger share of the proceeds from its own oilfields, then owned by BP, so that we could spend the money instead on our expensive new welfare state.
A British MI6 man called Monty Woodhouse (later Tory MP for Oxford) and the CIA's Kermit Roosevelt (grandson of President Teddy) bribed newspapers, paid mobs and suborned soldiers and police to overthrow Mossadeq. (Details of this have actually been published by the CIA.) They succeeded. But bitter memories of that event lay behind much of the savagery of the 1979 revolution, in which anyone who might have been an ally of the West was ruthlessly imprisoned or murdered.
At the end of this renewed denunciation - which I think reveals the mullahs' determination to keep Iran away from its natural friends in the West - a cheerleader urged the seated crowd into cries of 'Marg Bar Amrika' (Death to America!) and 'Marg bar Angeleez' (Death to England!). The shouts sounded listless and perfunctory to me, a duty done rather than the passion I had seen at Mashhad.
My next destination was the tomb of the poet Hafez in Shiraz - until the revolution, a centre of wine-growing, appropriately enough, for Hafez writes about love and wine. His verses are revered by the Persian people and much distrusted by the Islamic authorities, yet he is too great to be suppressed.
I fell into conversation with two women. They said the schools taught that Hafez's references to love were about the love of religion, and that when he spoke about the joys of wine they should know that prayer had the same effect as wine. 'How would they know if prayer was like wine, since they aren't allowed to drink?' I asked them, and the two giggled. They hadn't thought of asking that. But they will next time.
A few miles away are the great ruins of Persepolis, a historical monument equal to the Pyramids. The ruins were dug out of the sand only 150 years ago, and there are strong rumours that the Ayatollahs wanted to destroy this inconvenient proof that Persian civilisation existed long before Islam. Fortunately, they did not.
I went on to the glorious city of Esfahan, a treasure-house of art and architecture that would be on every tourist itinerary were it in Europe. In the great square, I was accosted by several Iranians anxious to talk. I met two contrasting groups of schoolgirls. One group, all equipped with the coolest possible mobile phones, were deeply worried. One said: 'We are all sure there will be war with the West this summer.' This is specially frightening here, since the city hosts one of Iran's nuclear sites.
The other trio - one severely veiled, one more adventurous and one positively brazen with inches of hair exposed - were angered by Western threats of sanctions and worse. 'The more you threaten us,' the severe one said, 'the more we will rally round our government and the closer we will be to them.' In this they echoed almost every conversation I had had in Iran.
As one veteran of the Iran-Iraq War had said: 'If you had come here before the Iraq invasion, lots of us would have said, 'Please, come and invade us, come and save us.' America was the most popular country in Iran then. But we have seen what liberation has brought to Iraq and Afghanistan, and if you came now we would certainly fight, not like the Iraqis, but from the very start.'
On the road north to Tehran, I passed close to Natanz, the supposed centre of Iran's atomic programme. Natanz is an attractive town, where it would have been pleasant to stop for a glass of tea. I chose not to, to avoid any suggestion of spying. But a few miles north, the government had provided spectacular evidence of its warlike posture. On either side of the busy public road, anti-aircraft guns pointed at the sky.
It was as if, where the M4 runs reasonably close to the Aldermaston nuclear weapons plant, the British Army had installed flak batteries. As a military precaution against modern jets, they would be useless. But they help create the atmosphere of tension that keeps the ayatollahs and the people side by side, and so keeps Iran and the West apart.
My final destination was the holy city of Qom, where the ideas of the 1979 revolution were born. I had expected something dark and oppressive. Instead, I found a kind of Shia Blackpool, brightly lit streets full of busy shops selling cut-price Korans and also the local delicacy, a sweet pistachio nut brittle. Iranians, like our own forefathers, see nothing strange in mixing pleasure and faith.
Mullahs patrolled every street. If you watched a corner, a mullah would come round it, brown-robed and turbaned. There were mullahs upright on motorbikes, mullahs surging off buses or clambering on to them, mullahs with briefcases.
The only dark place was a painfully moving war cemetery at the gates of the shrine, paved with gravestones and walled with propaganda posters.
Beyond, the shrine glittered with gold and polished mirrors, floodlit and sparkling merrily in the night. And there I met a mullah who wanted to argue. Like all dogmatists, he was stuck in a circle. The Islamic republic had been a success, despite retreating so far from its original rules. The reforms by the last, liberal president, Khatami, had been made to strengthen Islam in Iran, even though they had relaxed many of the Islamic laws. But what he really wanted to talk about was the British sailors.
'They were spies,' he insisted, and when I said that spies didn't usually wear uniform, he retorted that this would be a typical devious British trick. Then he criticised the way they had behaved when they got home, claiming they had been mishandled when they had been well treated. I didn't feel like contradicting him.
At that point he looked at me sternly. 'You won't behave like them when you get home, will you?' he asked. And when I said that I really rather hoped not, he suddenly embraced me and gave me a great smacking kiss on both cheeks.
Despite the mullah's unwanted kisses, I am sticking to my view. By threatening Iran, we only help its rulers keep the wavering support of their people and strengthen their alliance with Muslim hardliners elsewhere.
Iran is not a serious threat to us, and if we treat it as one we will be tumbling into yet another foolish trap, devised by silly, ignorant politicians, from which it will take decades to escape.