There is a renewal of belief that the missing 12th imam will return, writes Lara Marlowe in Jamkaran
The thousands of Iranians who flock to Jamkaran mosque every Tuesday night don't think of themselves as superstitious or politically exploited.
They are not even aware that intellectuals in north Tehran and some reformist clergy are alarmed by the Mehdi revival.
The new president, Mahmoud Ahmadinejad, shares their fervent desire for the return of Mehdi, the 12th imam, who disappeared in Samara, Iraq, in 941 AD.
Ahmadinejad has brought his entire cabinet to pray in the shrine here. Rumour has it that Ayatollah Khamenei, the supreme leader of the Islamic Republic, sends his assistant to Jamkaran every week to have his appointment book approved by Mehdi.
For Mehdi never died, he has been wandering around the earth for 1065 years "doing his job as an imam", one believer tells me. He is the Christ of Shia Muslims, the name they utter in moments of despair, the one who suddenly appears in human form to rescue them from the worst difficulties.
But because Mehdi is hidden, you mustn't tell anyone you've seen him. It is forbidden by the hadith (sayings of the Prophet Muhammad), as is claiming you know the date of his return.
Hossein Afshar Tous (71) brings his wife Effat (60), their children and grandchildren to Jamkaran mosque every Tuesday to pray for the return of Mehdi. The family arrives early and picnics on the esplanade in front of the mosque. Tous, a wheat farmer from the countryside south of Tehran, is a true revolutionary.
He proudly shows me his Basij (militia) membership card and his credentials as a village councillor.
When the new moon rises every month, he kisses the image of Ayatollah Khomeini on the 10,000 rial banknote by the light of the moon, for good luck.
As we eat pistachios with tea, Tous tells me how a thief came to Jamkaran in ancient times to steal carpets from the mosque. Because it's a holy place, he ran around in circles and never found an exit.
Tous met Imam Khomeini in his dreams once, a few months after the revolution. "Imam was wearing shoes without heels, so I took a hammer and nails and put heels on. He asked me how many children I had and said I would be rewarded. A few days later, the komiteh gave me five hectares of land."
Before the shah fell, Tous worked with an American oil company.
"The American engineer used to urinate in front of us and yell at us," he recounts. "We Iranians know how to overcome people with ruse. One day, I was driving with the American in the desert. I stopped the car and said it was broken. He started yelling, so I told him to get out and look under the bonnet. I drove away at high speed."
The Jamkaran pilgrims pray for other things besides Mehdi's return: a theology student from nearby Qom has come to thank Mehdi for curing his nervous disorder, caused by too much study.
An Afghan Hazara refugee asks Mehdi for better treatment in Iran. "They won't let us attend university," she complains. "They are rude to our children in school and we are Shia like them."
One tale says a mullah used to gather up the little letters left by women in the dry well where Mehdi allegedly hid from his enemies. Many of the letters said, "Mehdi, send me a husband". The mullah sent a man to the address on the note, for a temporary "pleasure marriage".
Two middle-aged sisters and their mother have driven six hours from Isphahan to pray at Jamkaran. "I am asking Mehdi to destroy America," says Shahrbanou (45). "She means only the bad Americans," her sister Khadijana (52), explains, worried I'll be offended.
"We all love Ahmadinejad," says Shahrbanou. "He's a believer. He is with God. In the time of [ former presidents] Khatami and Rafsanjani, Islam was going to die."
At Imam Sadig university in Tehran, Prof Mohammad Hadi Homayoon is delighted to hear me say there's a Mehdi revival.
"It started with our revolution," he explains. Homayoon believes that "practically every verse in the Koran" alludes to Mehdi. By reading through the lines, one can know the fate of the world.
Before Mehdi returns, Homayoon says, "the world will grow very bad, full of injustice, wars and epidemics. This will pave the way.
"Imam Mehdi will begin from Mecca. The internal situation in Hijaz [ Saudi Arabia] will be chaotic. He will go from Mecca to Iraq to al Qods [ Jerusalem], where Christ will join him. The Christians who believe in Christ will believe in Imam Mehdi and they will pray together."
Islam has no battle of Armageddon, but the small minority of humans who know good from evil but who choose evil - the mustakbireen ("maybe Jews", Homayoon says) - will fight Mehdi, Christ and the faithful. "It will be a real war," Homayoon says. "Maybe with guns, planes, tanks and missiles. I'm not sure."
Does the professor think the looming war between the US and Iran is the war of the end of the world, the war with the mustakbireen?
"Personally, I believe it," he answers. "It may be the day we are waiting for. I hope for the least possible bloodshed."
Ahmadinejad's election was seen by many as a sign that Mehdi's return is imminent.
"I think that he believes as I do," says Homayoon. "He believes strongly in Mehdi. After the war, there will be one world government - an Islamic Republic of the World - and everyone will live in peace."
Ahmadinejad's enemies say that he and George W Bush, a born-again Christian, are two of a kind. Prof Homayoon rejects the comparison, saying Bush doesn't really believe the end of the world is nigh. "He pretends, but he's not sincere. If he was a real follower of Christ, he wouldn't do what he's doing.
"He and his entourage know the Islamic revolution is spreading throughout the world, and they want to stop it, to prevent the end of time. He is among the mustakbireen. This gang is what we were waiting for."