Driving into town from the small Midwest airport where Carrie Young and her husband had met me off the plane, she pulled a large picture from the back seat of the station wagon. Framed in gilded-gold, the picture showed the couple and their three children posing with an elderly, chubby-faced Indian man with an ostentatious Afro haircut, dressed in a red robe. Staring out of the picture, it seemed the Youngs were shining with happiness. "And to think," said Carrie, "this is the man we used to think was God."

The Youngs were what Americans call "straight arrows": honest, decent and truthful. A handsome, clean-cut couple in their mid-40s; both worked in the computer industry. The past year, said Jeff, had been difficult, what with all that had happened, but they were pulling things together.

A year ago, their son Sam had come to them with a shocking assertion: Sathya Sai Baba, he told them - the man the Youngs had revered as God for more than 20 years - was, in fact, a sexual abuser. Over the course of four years, in his ashram, while Sam's parents sat a few metres away - thrilled that their son should be in such close proximity to the divine, secure in their belief that the god-man was ministering to their son's spiritual welfare - Sai Baba was actually subjecting him to sustained and systematic sexual abuse. "You'll meet Sam at the restaurant," said Carrie. "He's prepared to talk about this. He thinks it's important too."

Sam was a tall, blue-eyed, dreadlocked boy with a look that could only be described as angelic. For the next four hours, they told me the story of how they had come to Sai Baba; of their spiritual aspirations, the dreams, the visions, the miracles - and the nightmare their lives had turned into. And always, throughout the conversation, the same question repeated itself: how could it possibly have come to this?

For more than 50 years, Sai Baba has been India's most famous and most powerful holy man - a worker of miracles, it is said, an instrument of the divine. His following extends not only to every corner of the Indian sub-continent, but to Europe, America, Australia, South America and throughout Asia. Estimates of the total number of Baba devotees around the world vary between 10 and 50 million.

To even begin to appreciate the scale and intensity of his following, it is necessary to have some understanding of what his devotees believe him to be, and of the powers that are attributed to him. Among his devotees, Sai Baba is believed to be an avatar: literally, an incarnation of the divine, one of a rare body of divine beings - such as Krishna or Christ - who, it is said, take human form to further man's spiritual evolution.

According to the four-volume hagiography written by his late secretary and disciple, Professor N. Kasturi, Sai Baba was born "of immaculate conception" in the southern Indian village of Puttaparthi in 1926. As a young boy, he displayed signs of miraculous abilities, including "materialising" flowers and sweets from nowhere. At 13, he declared himself to be the reincarnation of a revered southern Indian saint, Shirdi Sai Baba, who died in 1918. Challenged to prove his identity, Kasturi writes, he threw a clump of jasmine flowers on the floor, which arranged themselves to spell out "Sai Baba" in Telugu.

In 1950, he established a small ashram, Prasanthi Nilayam (Abode of Serenity) in his home village. This has now grown to the size of a small town, accommodating up to 10,000 people, with tens of thousands more housed in the numerous hotels and apartment blocks that have sprung up around. There is a primary school, university, college, and hospital in the ashram, and innumerable other institutions around India bearing Sai Baba's name. In India, his devotees include the former prime minister, PV Narasimha Rao, the present Prime Minister, Atal Bihari Vajpayee, and an assortment of senior judiciary, academics, scientists and prominent politicians. Unlike other Indian gurus who have travelled in the West, cultivating a following among faith seekers and celebrities, Sai Baba has left India only once, in the '70s, to visit Uganda. His reputation in the West spread largely by word-of-mouth. His devotees tend to be drawn from the educated middle-classes.

It is said that as an instrument of the divine, Sai Baba is omniscient, capable of seeing the past, present and future of everyone; his "miracles' include materialising various keepsakes for devotees, including watches, rings and pendants, as well as vibhuti or holy ash. Like Christ, he is said to have created food to feed multitudes; to have "appeared" to disciples in times of crisis or need. There are countless accounts of healings, and at least two of his having raised people from the dead.

Sai Baba's teachings resemble a synthesis of all the great faiths, with a particular emphasis on Christian charity, enshrined in his most ubiquitous aphorism, "Love All, Serve All".

The principal event in Prasanthi Nilayam is darshan, in which Sai Baba emerges twice daily from his quarters adjacent to the main temple and walks among the thousands of devotees seated on the hard marble floor. Hands reach forward to touch his feet or to pass him letters of supplication. Occasionally he pauses, to offer a blessing or to "materialise" vibhuti in an outstretched hand. It is during darshan that Sai Baba, by some unseen criteria, chooses people from the crowd for private interviews. Some devotees might wait for years.

Inevitably for such a potent figure, Sai Baba has, for years, been the subject of rumbling allegations of fakery, fraud and worse. But he has proved remarkably immune to controversy, the accusations doing little to dent his growing following or the esteem in which he is held. But all that, it appears, is about to change.

In recent months, a storm of allegations have appeared - spurred by a document called The Findings, compiled by an English former devotee named David Bailey - which threaten to shake the very foundations of Sai Baba's holy empire. Sai Baba may represent an ancient tradition of belief, but the instrument of accusation against him is an altogether modern one. Originally published in document form, The Findings quickly found its way on to the Internet, where it has become the catalyst for a raging cyberspace debate about whether Sai Baba is truly divine or, as one disenchanted former devotee describes him, "a dangerous paedophile".

David Bailey became a devotee of Sai Baba in 1994, at the age of 40, drawn by an interest in the guru's reputation as a spiritual healer. "I couldn't see him as a God," says Bailey, "but I did think, this could be a great holy man who has certain gifts."

An extrovert man, Bailey quickly became a ubiquitous and popular figure among devotees. He travelled all over the world, speaking and performing at meetings and would visit the ashram in India three or four times a year. Over the course of four years Bailey claims to have had more than 100 interviews with Baba. At Baba's instigation, Bailey married a fellow devotee, and together they edited a magazine to propagate Sai Baba's teachings. But the closer he came to Sai Baba, Bailey told me, the more his doubts multiplied. The miracles, he concluded, were B-grade conjuring tricks, the healings a myth, and Baba's powers of being able to see into people's minds and lives merely a clever use of information gleaned from others.

Bailey's dwindling faith was finally crushed when students from the college came to him alleging that they had been sexually abused by the guru. "They said, `Please sir, can you go back to England and help us."' They were unable to tell their parents because they were afraid of being disbelieved, and feared for their personal safety.'

Shocked by the allegations, Bailey severed his association with Sai Baba and began to assemble a dossier of evidence from former devotees around the world. The Findings is a chronicle of shattered illusions. It contains allegations of fakery, con-trickery and financial irregularities in the funding of the hospital and over a Sai Baba project to supply water to villages around the ashram, which is habitually trumpeted as evidence of his munificence.

Some of these allegations have been aired before. But the charges contained in The Findings are of an altogether different magnitude. They include verbatim accounts of abuse from devotees in Holland, Australia, Germany and India. Conny Larsson, a well-known Swedish film actor, says that not only did Sai Baba make homosexual advances towards him, but he was also told by young male disciples of advances the guru had made on them.

In April, Glen Meloy - a retired management consultant and a prominent Californian devotee of some 26 years standing - received a letter from an American woman who had read The Findings on the Internet. Her 15-year-old son, she said, had also been abused. Included in the letter was a four-page statement from the boy himself alleging multiple sexual abuse.

Meloy launched his own Internet campaign to spread the allegations. The effects of this have been enormous. There has been a rash of defections from Sai Baba groups throughout the West. >From other devotees, however, the response has been one of disbelief and denial. "Sai Baba," says Bailey, "is a simple sex maniac who's on an ego trip, after money, after power. He is a sheer conman." No, say others, "Sai Baba is God."

The Young family are not among those listed in The Findings, but the story of how they had come to Sai Baba was not atypical. In the early '70s, Jeff had become interested in "the spiritual quest", initially through psychedelics, then through yoga and meditation. He learned of Sai Baba through a friend, and in 1974, at the age of 18, visited India for the first time.

Three weeks later Jeff had a private interview with Sai Baba. "And I remember feeling peace like I had never felt before; feeling loved like I'd never been loved before." He returned to Los Angeles, where he lived in a community with fellow Baba devotees. He met Carrie, whose childhood had been characterised by parental abuse, and her teenage years by drug abuse. She, too, became a devotee of Sai Baba. They married, moved to the Midwest and started to raise a family. Over the years, they visited Sai Baba from time to time. They founded a community, home-schooled their children according to his teachings, and strove to lead a life of purity and self-discipline.

Then, in 1995, things began to change. Their son, Sam, who was now 16, visited the ashram with a family friend and was singled out for a private interview with Sai Baba. Eighteen months later, the Youngs returned to Puttaparthi; again Sai Baba singled out Sam and called him and the family for an interview. "He made [a big fuss of] our group," said Jeff. "He materialised a ring for my son. He told everybody that Sam had been a great Shirdi Sai devotee in a previous life - he just poured it on." During the course of that visit, the Youngs were called for seven interviews, while Sam had some 20 private meetings. The family felt blissfully privileged. He materialised rings, watches, bracelets, gave them robes and the silk lungi he wore next to his skin.

The following year, the family returned to Puttaparthi three times. On each occasion they would be gifted with two or three interviews. Sam had twice as many. "We had no idea what was going on," said Jeff.

In 1995, Sam had come to his father. In a private interview, he said, Sai Baba had "materialised" some oil in his hand, unbuttoned Sam's trousers and rubbed his genitals. Jeff told his son he had had a similar experience when he first met Sai Baba at 18. "I said to Sam, what did you think about it? He said he didn't feel there was anything sexual about it; it was like Sai Baba was doing his job. And I'd kind of had that experience. A doctor gives a boy an exam. I'd taken it as some kind of healing." Thereafter, Sam said nothing about his experiences.

What had actually occurred was this: from anointing with oil, Sam told me, Sai Baba's advances had grown progressively more abusive and forceful. Sai Baba, he said, had kissed him, fondled him and attempted to force him to perform oral sex, explaining that it was for "purification". On almost every occasion Sai Baba had given him gifts of watches, rings, trinkets and cash, in total around $10,000. He had told him to say nothing to his parents. When Sam asked Baba why he was doing this, he would tell him it was because Sam was "a special devotee - that it was a great blessing". When Sam attempted to resist, he said, Baba would threaten not to call his parents for any more interviews. "I felt obligations, to my parents, our friends, all the thousands of people sitting outside who all wanted to be in the position I was in, not knowing what was really there.

"And then the big thing was the concept that he is God, from day one, so when he says, don't tell anybody ..."

In fact, Sam did tell somebody. He confided what was happening to two other American teenagers who were students at the Puttaparthi college. They had had similar experiences. "They justified it as a divine experience. But he was doing things to me that I didn't want to do, and I was just letting it happen."

In 1998, according to Sam, Sai Baba attempted to rape him. The following year, the day before the family were leaving for Puttaparthi, he told his father he did not want to see Sai Baba alone, without specifying why. Jeff sensed something was amiss. "I told him, you must always be true to your conscience. The family don't care if we never have another interview again." In Puttaparthi, Sam was again called for a private interview. When Sai Baba attempted to get him to perform oral sex, Sam walked out for the last time, although it would be some months before he summoned the nerve to tell his parents. Jeff said it took some weeks to "process" what they were hearing. "We knew that Sam was telling the truth, but I still asked myself, what could this mean?"

The Youngs contacted a leading figure in the American Sai Baba organisation. "He said it must be some kind of test," said Jeff, "and for a moment we felt better."

Then Dr Michael Goldstein, the man in charge of the entire Baba organisation in America, flew in from California to meet them. "He said, we've got to talk to Baba about this; words are not enough; faith must be restored." Goldstein flew to India. He returned to tell the Youngs that Sai Baba had told him "he is pure", and that Goldstein accepted that. He asked Jeff if he thought his son might be delusional. The Youngs no longer speak with Goldstein.

A senior devotee, a trustee for the Sathya Sai Baba Society of America, Jerry Hague, told me that he and his wife had been devotees for 25 years. He was deeply shocked at the allegations and could not begin to understand them.

"All I know in my heart is that Swami is the purest of the purest, and that everything he does is for the highest good of everybody." This denial - Sai Baba is God, God doesn't do these things - was a theme that was echoed by innumerable other devotees I spoke to in America and Britain.

Among those people named in The Findings is Dr D Bhatia, the former head of the blood bank at the Sathya Sai Super Speciality Hospital, who, it is claimed, had a longstanding sexual relationship with Sai Baba. Bhatia resigned from his post at the hospital in December 1999 and is now an administrator at a hospital in New Delhi.

Contacted by phone, Bhatia said that he had become a devotee of Sai Baba in 1971, at the age of 20, and that he had had sexual relations with Sai Baba for "15 or 16 years". In that time, he said, he was also aware that Sai Baba had relations with "many, many" students from the college and school, and with devotees from overseas.

One of the most remarkable facets of this controversy has been the role of the Internet. Even 10 years ago, it is doubtful whether the allegations against Sai Baba would have spread so far and so fast.

Conny Larsson has set up a support group for those claiming abuse by Sai Baba, and says he receives some 20-30 e-mails a day from victims "crying out for help. You cannot leave these people in the desert".

In America, the campaign organised by Glen Meloy has concentrated on "e-bombing" copies of the allegations to senators, the White House, the FBI and Indian newspapers. The most conspicuous success of the campaign came in September when Unesco withdrew its co-sponsorship and participation from an education conference at Puttaparthi, citing "deep concern" over the allegations of sexual abuse.

For all the allegations laid against him over the years, Sai Baba has never been charged with any crime, sexual or otherwise. And his exalted position in India has until now kept him safely insulated from any kind of public inquiry.

Among former devotees, there is a sense of shock, betrayal, anger - a hunger, if not for revenge, then for accountability. "We know that many victims have been physically molested," Glen Meloy told me, "but in reality all the former devotees have been spiritually raped because we chose to believe that this man was the highest. I certainly considered him to be the God of gods, the creator of all creation, my friend, my everything. The intense desire I have to expose him now is directly proportionate to the amount of devotion I gave him."

Sitting in the restaurant in a small, homely Midwest town, Jeff Young struggled to understand what had led him to believe that an Indian guru could be God.

Looking back, he said, when Sam finally told him about the sexual abuse, he didn't find it difficult to believe at all. "I realised, I'd really known this for a long time but didn't really know it." Jeff shook his head. " You ask yourself, how could millions of people be wrong? How could millions of people be tricked? .. We'd spent 23 years raising our family to believe in him, going upstream against a river. You think, how could I have been so wrong?"

Whether he is divine, "a demonic force", as Glen Meloy describes him, or simply an accomplished fakir and confidence trickster, Sai Baba has said nothing publicly about the allegations. When contacted, K. Chakravarthi, secretary of the Puttaparthi ashram, said, "We have no time for these matters. I have nothing to say."

Sai Baba's principal English translator, Anil Kumar, said every great religious teacher had faced criticism. Allegations had been made at Sai Baba since childhood, "but with every criticism he becomes more and more triumphant."