By Steve Boggan

I am deep in the Amazon rainforest, anxiously losing my mind as the world begins to disintegrate. Around me, all sense of distance is wrapping itself up like spatial origami, slowly shrinking until an entire dimension has disappeared. A moment ago, I was surrounded by 200 people dressed in white and singing like angels, but now they occupy the same space as me... if that makes any sense.

Wherever I look, that is where I am. I can see everything from every angle, all at the same time. In fact, I feel I am everywhere. Outside, in the forest, the thrum of frogs and cicadas drowns out the sound of shrieking monkeys. Below me, the floor is shimmering, vanishing in waves like a spent mirage. Behind, I feel a cold vibration on my neck and sense a growling malevolence. I turn and see a red door, bulging at the hinges. Overcome with dread, I push hard to keep it closed, and all the while I feel a horrible nausea.

When will this end, I am thinking. And, with sweat running down my forehead, how can I survive it? Welcome to the Church of Santo Daime, one of the fastest growing religions in the world. Its mixture of Christianity, South American shamanism and African animism is proving irresistible to thousands of new believers across the globe. But it is its central sacrament, ayahuasca, a powerful hallucinogenic brew made from rainforest plants - a brew that I have just drunk - that makes the Church so appealing to some yet so controversial to others.

Santo Daime groups believe that ayahuasca, or Daime, as they call it, is a manifestation of Jesus Christ that brings them closer to God. Their visions, sometimes terrifying, sometimes blissful, help them to make sense of themselves, their universe and their god. Theirs is a young church - less than 80 years old - but in recent times it has spread throughout South America to the US and Canada, the Far East and Australasia, across mainland Europe and on to the UK.

According to followers I have interviewed, the number of worshippers in Britain is in the mid-hundreds, operating in London, Devon, Cornwall, Northern Ireland, Wales and Yorkshire. But these numbers are growing in spite of an obvious hurdle - the active ingredient in ayahuasca, dimethyltryptamine (DMT), is a Class A drug.

British Santo Daime groups meet secretly, always, as one put it, “afraid of the knock on the door” because of their (as yet untested) legal status. They worship in each other's homes, community centres, colleges and church halls, often telling landlords that they need them for choir practice. They never advertise and new members are allowed to attend strictly by invitation only. But among those in search of spiritual enlightenment - among weekend New-Agers too - the word is spreading; followers of Santo Daime claim that one session with ayahuasca is worth 100 hours of therapy.

If you don't have an invitation, then, but you want to attend Daimistas' worship, understand their beliefs and drink their sacrament, you might have to do what Domenico Pugliese (a photographer) and I did: travel 8,000 miles by plane, bus and boat to Céu do Mapiá, deep in the Amazon. This is Santo Daime's very own Shangri-la, a community of some 700 people living out their dream in the rainforest. Because here, as across all Brazil, the use of ayahuasca in a religious context is perfectly legal, treated even with deference by academics, politicians, medical researchers and theologians.

The Church of Santo Daime (“holy give me” in Portuguese) was born in the 1930s out of the experiences of a Brazilian rubber-tapper named Raimundo Irineu Serra, or Mestre (Master) Irineu, as followers call him. He was born in 1892 to African parents in Maranhão in the northeast of Brazil and travelled to Acre in the northwest in 1912 to find work during a boom time for the rubber industry. In 1930 he was given his first taste of ayahuasca by indigenous shamans - medicine men - and spent eight solitary days and nights in the rainforest, experiencing a series of visions and receiving instructions from the Virgin Mary, whom he called the Forest Queen, that formed the basis of a new religion.

It was predominantly Christian with an emphasis on nature - on the spirits of the rainforest - and it espoused spiritual growth through the drinking of ayahuasca during carefully defined rituals. In subsequent years Mestre Irineu shared his teachings, experiences and ayahuasca with growing numbers of fellow rubber extractors before building his own church, Alto Santo, on the outskirts of Rio Branco in Acre.

After the death of Mestre Irineu in 1971, the church split into various factions. The most important - which moved to Céu do Mapiá in the early 1980s - was led by one of Mestre Irineu's closest disciples, Sebastião Mota de Melo, or Padrinho (Father) Sebastião. It is this branch of the Church, also known as CEFLURIS (the Eclectic Centre of the Universal Flowing Light of Raimundo Irineu Serra), which is spreading fastest today.

To get there from the UK, we fly to São Paulo and on to Rio Branco via Brasilia. From here, there is a seven-hour bus ride along 200km of mud track (often impas- sable during the rainy season) to the Amazonian frontier town of Boca do Acre and the last leg of the journey, a haunting five-hour ride in a motorised canoe along the broad sweep of the red River Purus and its tributary, Igarapé Mapiá. Along the way we see pink dolphins, water snakes, squirrel monkeys, hummingbirds and kingfishers. At regular intervals, the canopied tributary narrows to just a few metres and Conrad's Heart of Darkness is called to mind. At several spots fallen trees have blocked the way and, in torrential downpours, we have to wrestle the canoe over them.

Finally, as the afternoon light begins to fade on the fourth day of our travels, we round one of hundreds of bends in the river and see a rudimentary wooden bridge from which children are jumping and laughing. We have arrived. As we climb up the bank, no one pays us much attention as they go about their business; we have come unannounced, but this is an open community.

High on a hill to our left is a star-shaped church above a lake; in front of us, a central grassy square surrounded by a handful of provisions stores and cafes. There are a few guesthouses, a school, a basic health centre and, on both sides of the river, winding paths with wooden homes on stilts branching off in all directions. The mood is relaxed and welcoming but natural, too. Relieved, I lay to rest thoughts of Jonestown-style cultism.

Our timing is fortunate; within a couple of hours a special ceremony is due to begin to commemorate the life and death of Padrinho Sebastião, the community's founder. This is one of the most important days of the Santo Daime calendar and there is a sense of excitement in the air; families, mostly descendants of Brazilian rubber tappers, begin wending their way to the church, the men and boys dressed in brilliant white suits, white shirts and blue ties, the women and girls in snow white with green sashes and sparkling tiaras. When worshippers see us at the foot of the church steps, they smile and invite us inside.

The men stand on one side of the church, the women on the other, and at the centre is a star-shaped altar around which the most senior Church members (including Padrinho Alfredo, currently the most senior) sit and orchestrate proceedings. There are prayers and then the first of 129 hymns is sung, with the congregation swaying, three steps to the left, then the right, along lines drawn on the floor to give everyone enough space. Such ceremonies can take up to 12 hours and, perhaps understandably, are referred to as “works” as they can be exhausting.

The ayahuasca that the congregation will drink every few hours throughout their ceremonies is made during each new moon from the vine of one Amazonian plant, bannisteriosis caapi, and the leaf of another, psychotria viridis. The vines are beaten by hand and then repeatedly boiled with the leaves until a brownish, bitter liquid is produced. It has been used by shamans since the time of the Incas as a medicine, as a tool used for self-enlightenment and as a window into the spiritual world.

After a while the shutter on what appears to be a bar is raised and one of the older members of the congregation invites the men to come and drink the Daime. The same happens on the women's side. The “barman” pours the brown liquid from a ceramic urn into large shot glasses and, one by one, the men drink. Many take their children too - here it is normal for babies to be given Daime as soon as they are born. The kids look thoroughly unfazed by the whole process and return to their rhythmic dancing but the sight of children being given a hallucinogen makes me feel uncomfortable.

I take my ayahuasca. It tastes awful, bitter and sour at the same time. And it is a fierce emetic, often making drinkers vomit and defecate. The Church, however, considers this a positive side-effect, a purging of negativity, darkness and malevolent spirits. In gaps in the singing - as beautiful as any choir I have ever heard - come the sounds of retching from the male and female toilets. I constantly feel on the edge of vomiting. And I wait.

After about half an hour, I begin to feel distant and slightly paranoid, imagining that people are looking at me. Straight lines begin to bend and I feel heavy and very tired. After a while, I am advised that it is time for another drink. Almost immediately my shrinking space and red-door hallucinations take over. These last for perhaps two hours and I decline a third drink, retreating instead to my wooden guesthouse where the Daime makes me re-live journeys and conversations with friends, family and lovers. I wake several hours later with not the slightest hint of a hangover. I feel refreshed and strangely uplifted in spite of what was a largely unpleasant experience.

And, as various people had predicted before I took the sacrament, the Daime had taught me something: my father died last year and I feel that the world behind the red door - which I never did allow to open - was filled with unresolved grief. The sacrament, regarded by Daimistas as a kindly teacher, was telling me that I ought to do something about that.

So, is this a Church we should be welcoming or is it just an excuse for people to take drugs? Is Santo Daime a serious religion and is ayahuasca really so important to its adherents? In Brazil, the use of ayahuasca in religious ceremonies was made legal in 1992 after two government-sponsored studies that established that Santo Daime was a valid religion and its use of ayahuasca was not recreational. These studies also found no negative effects on physical or mental health that could be ascribed to long-term usage. In fact, further research - most notably by Charles Grob, Professor of Psychiatry at the UCLA School of Medicine - has shown that ayahuasca offers potential in the treatment of depression and addiction.

Around the world, however, the practising of Santo Daime has been dogged by illegality, aside from a couple of notable exceptions. Religious use of ayahuasca in the Netherlands was assured after a court case in 2001. In the US, an offshoot of Santo Daime, the União do Vegetal (UDV), was granted the right to use it in its ceremonies by the Supreme Court in 2005. The case related only to the UDV, however, and the law covering other groups is still uncertain.

In Europe, followers have repeatedly run up against the law. There have been clampdowns and arrests in Germany (1999), Spain (2000, although the law has since been relaxed), France (2005) and Italy (2006). Daimistas also practise in Canada, Japan, Russia, Sweden, Greece, Australia, Switzerland and Denmark, all countries in which DMT is illegal.

Padrinho Alex Polari, one of the most senior members of the Church, seems pleased with its uptake around the world but says that it is not something the founders had expected. “We are not really looking to expand, but foreigners come here searching for answers to questions,” he says. He has a luxuriant white beard and smiling eyes. “Then they go home and more links are created from the outside world.” He says that countries to which Santo Daime is spreading should look to the success of Céu do Mapiá before judging it harshly. The community is involved in forest conservation projects and, as a co-operative, the cultivation of rice, bananas, corn, sesame, Indonesian pearl barley and cereals from the Amazon.

“The Brazilian Government conducted two studies with scientists, medics, artists and writers and concluded that the Daime was a positive force in our community, that it helped with personal development and was not harmful to health,” he says. “So they legalised its use.

“This is a spiritual community and we try to live spiritual lives. The work we do with the Daime leads to a higher knowledge of ourselves and creates a transformation within us to become better people. It is not something to be afraid of.” Edward, a 32-year-old mental health worker from London, has come to Céu do Mapiá as part of a three-month trip worshipping with Daimista groups across South America. He says he is fearful of what might happen to worship in the UK once its existence becomes widely known.

“In England, it is used on a more spiritual than religious plane by open-minded and thoughtful people - therapists, psychologists, care workers, doctors, artists and so on,” he says. “When you take Daime it can unsettle you and make you face difficult truths, but ultimately that helps you on to a better path and you feel light and love. We only want it to be kept low-key. We don't want to be isolationist, we just want to be free to follow our own path.”

Irina Shutova, 41, an engineer from North London, says she attends secret Santo Daime ceremonies in nearby Kentish Town. “I have been going for 2 years,” she says. “I found out about them from a very close friend. I had known him for ten years and he had been involved for three years before he took me. It is very secretive.

“I had never taken any kind of drug that altered consciousness but for many years I had been trying to follow a spiritual path, living in ashrams and doing studies, so I was already in a high state of consciousness. Then I tried the Daime and I experienced all my fears and doubts and everything you can associate with hell.

“When you take it, it can be very frightening and so intense because you cannot get out of it and you feel trapped and you have no control over anything. You experience all your negative rejections and all your dark places. But then it helps you to understand all this darkness and negativity and you begin to confront and deal with it.

“For me it is now everything; it is like swimming in a golden river of love, and of feeling loved by God. But this is only good for people who want to know about life, death, love and truth because that is what it tells you.”

Back home in the UK, the prospects for the religion remain in doubt. Edward believes the police know about Santo Daime's activities but are leaving it alone because its members are harmless. Practitioners in Brazil, however, told me that every month 2,000 litres of ayahuasca are brewed in Céu do Mapiá and sent out by air mail, the packages marked as “tea”, to followers around the world - including those in the UK. A Home Office spokeswoman told me that as far as the authorities were concerned, DMT was illegal and trafficking in it could result in prison sentences of up to seven years. Asked whether she thought defendants might not cite Article 9 of the European Convention on Human Rights, which guarantees freedom of thought, conscience and religion, she said that would be a matter for the courts.

The Roman Catholic Church, from which Daimistas have drawn much of their faith, refused to discuss their presence in Britain when I contacted it. However, in the US Supreme Court case in 2005, in which the União do Vegetal, the offshoot of Santo Daime, won its right to use ayahuasca, the Church supported it.

In a brief to the court, lawyers for the United States Conference of Catholic Bishops wrote: “[This] case exemplifies the inevitable conflicts that arise when the demands of religious conscience and belief, and the demands of the state to regulate society, clash.

“The issue becomes particularly significant where the Government's actions do not merely have an incidental or unintentional effect on religious practice, but rather where the Government has explicitly proscribed that which religion, equally explicitly, prescribes.” It remains to be seen, then, who will win the contest between the forces of law and order and those underpinning the right to practise one's religion when it finally comes to the UK. The individuals I met in the community were gentle, thoughtful and kind and I wish them luck.

All I know for sure is that I won't be taking ayahuasca again. If I ever open that red door, it will be with a clear head and a healthy sense of trepidation.