As Iran rushes towards confrontation with the world over its nuclear programme, the question uppermost in the mind of western leaders is "What is moving its President Mahmoud Ahmadinejad to such recklessness?"
Political analysts point to the fact that Iran feels strong because of high oil prices, while America has been weakened by the insurgency in Iraq.
But listen carefully to the utterances of Mr Ahmadinejad - recently described by President George W Bush as an "odd man" - and there is another dimension, a religious messianism that, some suspect, is giving the Iranian leader a dangerous sense of divine mission.
In November, the country was startled by a video showing Mr Ahmadinejad telling a cleric that he had felt the hand of God entrancing world leaders as he delivered a speech to the UN General Assembly last September.
When an aircraft crashed in Teheran last month, killing 108 people, Mr Ahmadinejad promised an investigation. But he also thanked the dead, saying: "What is important is that they have shown the way to martyrdom which we must follow."
The most remarkable aspect of Mr Ahmadinejad's piety is his devotion to the Hidden Imam, the Messiah-like figure of Shia Islam, and the president's belief that his government must prepare the country for his return.
One of the first acts of Mr Ahmadinejad's government was to donate about £10 million to the Jamkaran mosque, a popular pilgrimage site where the pious come to drop messages to the Hidden Imam into a holy well.
All streams of Islam believe in a divine saviour, known as the Mahdi, who will appear at the End of Days. A common rumour - denied by the government but widely believed - is that Mr Ahmadinejad and his cabinet have signed a "contract" pledging themselves to work for the return of the Mahdi and sent it to Jamkaran.
Iran's dominant "Twelver" sect believes this will be Mohammed ibn Hasan, regarded as the 12th Imam, or righteous descendant of the Prophet Mohammad.
He is said to have gone into "occlusion" in the ninth century, at the age of five. His return will be preceded by cosmic chaos, war and bloodshed. After a cataclysmic confrontation with evil and darkness, the Mahdi will lead the world to an era of universal peace.
This is similar to the Christian vision of the Apocalypse. Indeed, the Hidden Imam is expected to return in the company of Jesus.
Mr Ahmadinejad appears to believe that these events are close at hand and that ordinary mortals can influence the divine timetable.
The prospect of such a man obtaining nuclear weapons is worrying. The unspoken question is this: is Mr Ahmadinejad now tempting a clash with the West because he feels safe in the belief of the imminent return of the Hidden Imam? Worse, might he be trying to provoke chaos in the hope of hastening his reappearance?
The 49-year-old Mr Ahmadinejad, a former top engineering student, member of the Revolutionary Guards and mayor of Teheran, overturned Iranian politics after unexpectedly winning last June's presidential elections.
The main rift is no longer between "reformists" and "hardliners", but between the clerical establishment and Mr Ahmadinejad's brand of revolutionary populism and superstition.
Its most remarkable manifestation came with Mr Ahmadinejad's international debut, his speech to the United Nations.
World leaders had expected a conciliatory proposal to defuse the nuclear crisis after Teheran had restarted another part of its nuclear programme in August.
Instead, they heard the president speak in apocalyptic terms of Iran struggling against an evil West that sought to promote "state terrorism", impose "the logic of the dark ages" and divide the world into "light and dark countries".
The speech ended with the messianic appeal to God to "hasten the emergence of your last repository, the Promised One, that perfect and pure human being, the one that will fill this world with justice and peace".
In a video distributed by an Iranian web site in November, Mr Ahmadinejad described how one of his Iranian colleagues had claimed to have seen a glow of light around the president as he began his speech to the UN.
"I felt it myself too," Mr Ahmadinejad recounts. "I felt that all of a sudden the atmosphere changed there. And for 27-28 minutes all the leaders did not blink…It's not an exaggeration, because I was looking.
"They were astonished, as if a hand held them there and made them sit. It had opened their eyes and ears for the message of the Islamic Republic."
Western officials said the real reason for any open-eyed stares from delegates was that "they couldn't believe what they were hearing from Ahmadinejad".
Their sneaking suspicion is that Iran's president actually relishes a clash with the West in the conviction that it would rekindle the spirit of the Islamic revolution and - who knows - speed up the arrival of the Hidden Imam.
