Mark, now 53, is originally from New Zealand, but moved to Australia in 1984. A glazier and professional musician, he is contagiously optimistic and compulsively friendly. Rose is more reserved, but highly curious. She grew up in Spain and Paris and speaks several languages. They describe themselves as "idealistic". "We have always been interested in trying to come back to what seemed like a more natural, sustainable, fulfilling way of life," Rose tells me.

On that day in 1996, however, the couple were at a crossroads. They had just returned from two years in Spain during which they had struggled to find work. Now they were back in Sydney, living in an apartment in Coogee that belonged to Mark's brother. "We weren't exactly desperate, but we were at a loose end," Rose says. "We were hungry to make friends, to have a stable social life. I'd come to the conclusion that I didn't care who people were, I was just going to take them as they are."

After a while on the grass, Mark got up to walk around. Half an hour later he returned, clutching a pamphlet entitled A Brotherhood of Man. A friendly woman in a long dress with long hair had given it to him, saying, "You look like you need a home."

The pamphlet was produced by a group called the Twelve Tribes. "Where is the brotherhood of man that John Lennon imagined in his song?" it asked. "Where are the dreamers who have given up their possessions so that greed and hunger could be done away?"

The pamphlet mentioned Jesus, "the ultimate dreamer", who was referred to by his Hebrew name, Yahshua; it also quoted the Bible. But it rejected mainstream Christianity, denouncing it as "the whore spoken of in Revelations".

All this appealed to the Ilich family. "I'd always condemned the mainstream church," says Rose. "We'd also visited a few communes in Europe.

I said to Mark, 'If these guys are what they proclaim to be, this could be the community we're looking for.' "

A few days later, Rose called the number on the pamphlet and spoke to a woman called Shomrah, who invited them to visit the group at Peppercorn Creek Farm, a nine-hectare property it owns near Picton, south-west of Sydney.

The Iliches drove down that Friday, arriving at 7pm, in time for the evening gathering. They were greeted by a man with a long beard called Asher. (Asher's real name was Andrew McLeod, but like all members of the Twelve Tribes he had, upon joining the community, been given a Hebrew name.) Asher showed them to a guest room in the main farmhouse, where they left their bags. He then took them to a big tent full of people dressed in simple clothes. There were lounges and chairs and tables set with flowers and candles. There was music, too, a piano and an accordion, and beautiful, home-cooked food.

"I remember everyone was super interested in us," Mark says. "There was a guy called Yotham, who stayed with us all night, who was always telling me, 'I really like you, you seem like a really nice guy.' It was like we were part of an instant family."

Mark and Rose and the kids stayed that night and the next day and the night after that. In the morning they drove back to Coogee, got changed and went to the Glebe Street Fair, where the Twelve Tribes had a cafe stall similar to the one at Newtown. Yotham was there, with some of the musicians. Members of the group were dancing and they invited Mark and Rose to dance, too. "We are a family and you can be part of it," Yotham told Rose, as they spun about in the sunshine. "We can go grey together; our children will marry each other."

Rose and Mark were sold.

One of the first things the Iliches did was return to their flat in Coogee, accompanied by one of the community's "elders", a man named Israel. Israel told them what to keep and what to throw away. Most of their possessions - the kids' clothes, Mark's surfboard, books, toys - had a "spirit" about them and were deemed unsuitable. The Iliches had a small car, which they gave to the community, and some money in the bank, which they also handed over.

In January 1997 they were baptised, or "washed for their sins", in the creek that runs behind the farm, and given new names: Mark became Qatan ("childlike", in Hebrew); Rose became Asarelah (meaning "virtuous"). There were about 70 people in the community, including a dozen or so families, some of them second generation. "That's one of the things that attracted me," Rose says. "I thought, well, people have grown up here and decided to stay, so it must be good."

The Twelve Tribes group was founded in 1972, in Chattanooga, Tennessee, by a former high school guidance counsellor and carnival showman called Eugene Spriggs, known in the movement as "Yoneq". The group has 3000 members worldwide, with communities in the USA, Canada, France, Spain, Argentina, Brazil, Germany and England. The Australian "tribe" was established in the early 1990s by an American named Scott Sczarnecki (who has since left), and William Nunally, or Nun (pronounced Noon), another American who remains a senior figure at Peppercorn Creek Farm.

Following a hybrid of Judaism and Christianity, the group's aim is to re-create the 12 tribes of Israel, thereby ushering in the return of Yahshua, who will arrive like a "King coming for his bride when she is fully prepared for Him". Members use the Old Testament as a blueprint for their lives. The insistence on communal living, hard work and, most controversially, harsh child discipline, are all modelled on life in "the first church of Jerusalem", before the advent of the clergy, which the group abhors. Marriage outside the Tribes is forbidden, with elders and even Yoneq himself acting as matchmaker.

The group has been likened to the Amish, with whom they share some similarities, particularly in regard to marriage and modern technology. Wives must submit to their husbands, and are encouraged to have at least seven children. Condoms and the pill are forbidden. Mainstream medical care is likewise shunned, something observers have linked to what appears to be a higher than normal rate of stillbirths. (Rose had a stillbirth in 2001 and says she knew of five in her time at Picton.)

Community life is strictly regimented. Members rise at 6am (except on Saturday, the Sabbath, when they rise at 7am), woken by a blast of the "shofar", or ram's horn. There is a morning gathering, or "minchah", at 7am, which includes prayers and singing, followed by work, either in the farmhouse, kitchen or fields. (One of Mark's first jobs was to tend the farm's 30-strong flock of merino sheep.) The community also operates many businesses, including bakeries, cafes, house painting and demolition crews, to which Mark, and later, his son Abraham found themselves assigned. Children, meanwhile, are home-schooled using specially approved texts printed on site. There is no TV, internet, magazines, newspapers or radio. Members are discouraged from contacting former friends or family and do not vote.

Mark and Rose weren't particularly religious, but they were impressed by the group's commitment and the sense of the farm being "one big family". "One of their teachings is to 'Take counsel from the least', meaning everyone is listened to," Rose says.

Early on, Mark and Rose were each assigned a "shepherd", a senior member whose spiritual insight enabled them to act as a mentor. "My shepherd was a woman called Bakhirah," Rose says. "If I had any problems in my marriage, any concerns or troubles, I'd go to her and open up."

And there was a lot to open up about. The teachings, some of which come from the Bible and others from Yoneq, stress the deep iniquity of the outside world, a dark place in which the only light is one's conscience. Failing to follow your conscience inevitably sees one consigned for eternity to the "Lake of Fire". Members are encouraged to "renew your mind" - a phrase from the apostle Peter - and to be "an open book before your brethren", always "sharing" your sins, either with the elders, your shepherd, or at the gatherings.

The Iliches' sins were considerable. Rose, for example, had slept with men before getting married; she had also "rebelled" against her mother. Mark, meanwhile, had played drums in a rock band ("I had a 'drum spirit', apparently," he says). He had also surfed and smoked marijuana. "They present a very high standard," Rose says. "It's all you hear, all the time, and so you start judging yourself by this standard. Your thinking becomes very black and white. At the same time, they present themselves as the only way to truly obey God, whose spirit they embody. So if you disagree with the elders or your shepherd, you're disagreeing with God himself."

The pressure to confess was considerable. If just one member held back, God could not answer anyone's prayers that day. And so Rose would scour her mind daily for any hint of sin. "In the end you run out of things and your mind invents trouble." She also began examining Mark's conduct. "They told me Mark was 'worthless' because he'd been seeking 'worth' through other things, like performing music. In the past I'd thought his music was beautiful; now I started to see it as a sign of weakness."

Rose became suspicious of Mark, thinking he was "full of sin that he wasn't confessing". At the end of each gathering, having tendered their transgressions "like a lamb to God", the group would join hands and engage in a screaming session that lasted several minutes. "At the time it felt therapeutic," she says.

Mark and Rose were under the impression the group's teachings were drawn from the Bible. In fact, the majority come from the group's founder. Spriggs, 76, is a mysterious figure: a former football player, boxer and soldier, a charismatic evangelist whose rejection of "rote religion" in the 1970s proved popular with the "Jesus freaks" of the counterculture. Though initially predicated on an open-door policy - there was "no leader", and everyone was a "priest" - his movement has become increasingly fundamentalist and authoritarian.

"Spriggs regards himself as the Anointed One, with a direct pipeline to God," says David Pike, an ex-member of one the group's tribes, Manasseh, in the US. "He comes off as loving but is the perfect picture of a narcissistic cult leader. One thing I'll always remember is what he used to call a 'spirit check', when he'd come up behind a male disciple and slap his back as hard as he could and wait to see the person's reaction, whether he winced or jumped or brought his fists up. I hated it."

Spriggs is thought to live mostly in Hiddenite, in North Carolina, in an antebellum mansion the group bought in 2006. But he also travels a lot, flying from community to community, his every word transcribed into "teachings" (or "the anointing") which are published in Intertribal News, the movement's in-house newsletter.

Spriggs's teachings, some of which are withheld until members are deemed capable of "receiving" them, are frequently bizarre. He has said that "submission to whites is the only condition by which blacks will be saved" and that Martin Luther King was "filled with all manner of evil". (The group denies it is racist, pointing out that they have high-profile black members in America.)

The teachings are also minutely prescriptive, shaping every aspect of members' lives. Spriggs insists that men wear beards, since it was only the Romans who started shaving. He forbids wristwatches, which he considers a vanity, and has decreed that all members eat with chopsticks in order to speed the group's movement into Asia. Diet is strictly regulated: no sugar, chocolate, coffee or tea, with plenty of flax seed, whole grains and millet, and an emphasis on cultured foods, like yoghurt and kombucha. "At one stage chilli was strictly prohibited," Rose says. "Then it was permitted again."

All Twelve Tribes members are instructed to finish their showers with a cold rinse, which Spriggs believes boosts the production of white blood cells. When Rose asked her shepherd how cold it had to be, she was told: " 'Straight cold, even in winter, for one to two minutes.' If I tempered it with hot, I was allowing my 'flesh' to be stronger than me."

Michael Painter, who spent 18 years with the Tribes in the US and rose to become third in command, has described Spriggs's approach as "teeth, hair and eyeballs". "It was thought that if God doesn't control your teeth, hair and eyeballs, he doesn't have you."

But Spriggs's strictest teachings pertain to child-rearing. Children have a special place in Twelve Tribes eschatology, which holds that Yahshua can return only when God has, through the movement, brought forth 144,000 perfect male children, "so pure that fire comes out of their mouths". Raising obedient offspring then, is imperative. Children must at all times be "covered", a Twelve Tribes term meaning supervised by an adult. They must not play games (playing is "dissipation"). They must not have toys. They must not whistle. They must not engage in make-believe or fantasy, or possess books that anthropomorphise nature, depicting, for instance, a talking dog or a smiling sun. "At Picton, kids weren't even allowed to talk to one another unless covered by an adult, since this could only lead to 'foolishness', " Mark says.

According to Mark, unquestioning obedience is mandatory: children must reply "Yes, Abba" (Hebrew for father) or "Yes, Ima" to any parental command. Any breach earns a spanking with the "rod", a 50-centimetre-long plastic stick, one of which is kept above the door ledge in every room. Parents are instructed on how to use the "rod" in monthly child-training sessions and also in a 267-page Child Training Manual, a copy of which Mark and Rose received after their first year. Written by Spriggs, the manual insists that "you must make it hurt enough to produce the desired result" and that "stripes from loving discipline show love by the parent".

"It's called 'the rod and reproof', " Mark says. "The kids are not meant to cry. They're meant to 'receive' their discipline quietly. Then you tell them why you hit them and they say, 'I'm sorry, I'm sorry.' It becomes a ritual."

Children aren't beaten only by their parents. Any "covering" adult can "correct" them. Abraham was beaten regularly, by numerous adults, either on the hand (six strokes) or bottom (12). "The more you cried, the more you got spanked," he says. "If it was a lady and I was beaten on the bottom, my pants were kept on. But if it was a man, he put my trousers down and beat me directly on my skin."

The beatings started at the age of four. "The first time I cried a lot. But I stopped crying forever when I was 12." By then, he had decided to rebel. "I decided I would never do what they wanted me to do, unless I was beaten until I couldn't take any more pain, and then I would obey."

In 1984, alerted to claims of abuse, US authorities raided the group's Vermont headquarters, taking 112 children into care. (The raid was deemed unconstitutional and the children later released.) The group has been investigated for child abuse several times over the past decade in the US, France and Germany. In September this year, Bavarian police removed 40 children from two Twelve Tribes communities following a TV program that showed footage, obtained with hidden cameras, of adults beating six children with 83 strokes of a cane in the space of a few hours.

The group has repeatedly denied allegations of child abuse. Responding on its US website, it describes the Bavarian raids as "unjust" and suggests the authorities had been "manipulated by unseen spiritual powers".

The Iliches found the child discipline particularly difficult. Their oldest daughter, Undila, was largely compliant and their youngest daughter, Lebana, who'd been born in 1998, was still a toddler. But Abraham was problematic. "He was a normal boisterous boy, which to them is unacceptable," says Rose. "I ended up having to spank him almost constantly, for everything." Abraham soon became labelled a "rebellious element", something for which Mark and Rose were blamed. "We were bad parents," she says.

This became their signature stigma. In 2001, when Rose delivered a stillborn baby boy, she was told it was because she was "full of sin". "Mark's shepherd came into my room while I was still in bed and said it was 'God's kindness' that the baby had died, because it would be evil to bring a baby into the world with parents like us." Soon afterward, the elders forbade them from having sex altogether. "And we actually complied," Rose says.

Many times during our conversations I ask Mark and Rose why they didn't leave. "Leaving is not an option," Rose says. "You have to understand how brainwashed you become. You lose the ability to think critically."

They were also afraid. The Tribes consider an ex-member someone who was once enlightened and wilfully chose darkness, and who is thus more evil than an ordinary non-believer. "Nun told us that people who leave become prostitutes or homosexuals, that you'll suffer sickness, die an early death and go straight to hell."

One former member from Picton later told Rose how she had taken a flight to Auckland shortly after leaving. "She was terrified the whole time that God would make the volcanoes underneath them erupt, killing everyone on board."

Besides, there was little time to think. "You work the entire time," says Rose. "The first thing I'd do in the morning was report to my 'covering sister', who would give me my chores for the day - cooking, cleaning, child minding." Mark, meanwhile, found himself assigned to painting crews and construction and demolition teams.

The Tribes are nothing if not industrious. They own at least 24 businesses worldwide and are extremely well resourced, especially in America, where they operate furniture stores, kids' clothing outlets, a printing press, leather shops, soap factories, wholefood outlets, cafes, bakeries and several multimillion-dollar construction firms, the biggest of which, Builders of Judah, specialises in nursing homes and historic restorations. They also own a maté farm (maté is a tea-like herb) in Brazil, which according to David Pike, now makes "huge money for them".

In Australia, as elsewhere, members are not paid for their labour. "I'd regularly do 12-, 15-hour days," Mark says. "I built their Common Ground Cafe in Rozelle and their Yellow Deli in Katoomba. Every year we'd build the Common Ground Cafe at the Royal Easter Show."

The businesses were highly profitable. "Once I helped them carry $40,000 in cash out of the Easter Show. But I never saw a cent."

When Abraham turned 13, he was taken out of school - "they told me I had a bad influence on the other students" - and set to work, digging trenches and chopping trees. By the age of 14 he was working with Mark in a bakery in Lidcombe, where the Tribes made buns to sell at the Woodford Folk Festival.

"The bakery was the worst," Mark says. "For the first three weeks we slept on mattresses with doonas, on the ground, in a shed next to the bakery. We ate from the bakery, every night, doing 12-, 15-, even 20-hour days."

After 18 months at the bakery, Mark snapped. "I just said, "F... this, I'm leaving.' I didn't tell Rose - anything I told her, she'd tell the elders. So my son and I just pissed off. We hitched a ride to Sunnyholt Road. I had some spare change in my pocket and I called my brother, Peter, who lived in the Blue Mountains and told him to pick us up."

Mark and Abraham slept at Peter's house that night. But the next day, Israel turned up. "Israel had met my brother and he knew where he lived. He also knew that we had next to no money and that I'd be at Peter's place."

Mark and Abraham surrendered and were driven back to the community.

Mark's family, most of whom live in New Zealand, never had any suspicions about the Twelve Tribes. "They just thought we were in a nice Christian community," he says. But Rose's family was different. "We knew from the beginning that it was a cult," says Rose's sister, Cathy Cruzado, who lives in Paris.

In 2000, Cathy and her brother Henry made plans to visit Rose in Sydney. But when Rose told the elders of their imminent arrival, all hell broke loose. "Nun became convinced my family was coming to get me," Rose says.

Within a week, Rose, Mark and the three children were on a plane to Spain, where they were installed in a Twelve Tribes community in Zeberio, in the Basque Country. Rose's mother lived nearby, in Laredo, just 20 minutes' drive away, but Rose was not allowed at first to visit her. Instead, she was instructed to call Cathy and Henry and tell them that she and the family were in Boston. "The whole time, one of the Spanish leaders, a guy called Yowcef Rodriguez, was sitting next to me," Rose says. Cathy was upset and cancelled her flights. But Henry decided to go anyway, visiting the community in Picton, where he was served tea and cake "by robotic looking ladies wearing large skirts".

"I talked to the leader," says Henry. "He was courteous and charming until I asked him his reasons for hiding my sister, when he laughed in my face and replied that he had no idea of Rose's whereabouts."

Henry would make a total of five trips to Australia over the next decade, often with Cathy. They contacted Matthew Klein, an ex-Twelve Tribes member, for help and worked with Melbourne cult buster Raphael Aron. "I travelled 100,000 kilometres and saw my sister once, for a total of 10 minutes," Henry says. "It was in 2004 and Rose had finally agreed to meet me at Peppercorn Creek Farm."

Henry had brought a rolled poster of the Cruzado family tree since the 16th century, to show Rose that she already had a family. But Rose rebuffed him. "I was scared stiff of Henry, because the elders had been saying he was part of an anti-cult movement and that he'd kidnap me and the kids."

The minute Henry appeared, Abraham and his sisters were whisked away by an elder and hidden in the roof of the main building. "I was devastated," Abraham later recalled, "because I knew I'd just missed the best and perhaps the last chance to escape."

Dodging Rose's family was surprisingly easy: whenever Henry showed up, the family would simply be shuffled between a network of properties - an apartment in Leura, a house in Burwood, a hotel in Lithgow. At one stage the Tribes rented them a bungalow near Parramatta, then a house on the beach in Coledale, and later a home at Seven Mile Beach, near Gerroa. The elders were so paranoid about Rose's family finding them that they wouldn't allow Mark to renew his New Zealand driving licence. "They thought the authorities might use it to track us," Mark says.

Mark enjoyed living at Gerroa; for one thing, it meant he wasn't slaving his guts out. It also meant he could go surfing again. "I'd found this board in the rubbish and repaired it," he says.

But one day, when Mark and Abraham were out in the surf, some elders paid a surprise visit. "Man, were they angry," says Mark.

The elders took the family back to the farm where they staged a meeting or "cohol", interrogating Mark for five hours. "They just hammered me," he says. "They were quoting verses from the Bible, telling me I 'loved the world', and that anyone who 'loves the world would lose their life'. "

Their solution was to split up the family, sending Mark and Abraham away, firstly to Katoomba, then to Bargo, while the women stayed on the farm. "Rose was allowed to visit me from time to time," says Mark, "so that I could see Lebana, who was still only little."

Throughout the mid 2000s, Mark and Abraham were allowed to come back to the farm from time to time to reintegrate. But Abraham would invariably do something "worldly" - cut his hair, smoke a cigarette, wear his trousers low - and be reprimanded. Then, when Abraham turned 15, the elders asked if he would like to "get washed", or baptised. "You can all get f...ed," he told them. "The elders almost had a heart attack," Mark says. "After that, they sent us away again, to this farm they own in Bigga."

The property, near Crookwell in the NSW southern highlands, was 460 hectares, with no power, water or house. "We just lived in this shed," Mark says. "Drank rainwater off the roof. They put a phone on for us and gave us gas cylinders to cook with. And every few weeks, Rose would visit." Their job was to chop wood, which was taken to Picton for heating. But Mark was increasingly disillusioned. "I was just so pissed off by then. Rose was in turmoil, too."

Then, in 2009, the elders sent Mark and Abraham to New Zealand. "They just wanted us out," he says. "So they gave me a couple of hundred dollars and said, 'Your New Zealand family can look after you.' "

It was in Auckland that Mark finally decided to leave the group. "I rang Rose and said, 'I think I'm leaving.' She said, 'My life is with you, I'll come with you.' "

Mark had the family sent over, ostensibly just to visit. Once there, he told them of his decision. Abraham was thrilled: "That's the best thing you've ever told me," he said. But Undila was devastated. She didn't want to leave, and began crying. She was due to marry Erez, a young man who had been sent over from the community in France. So Mark let her return. "That was the stupidest thing I ever did," he says now.

The family spent a year in Auckland before returning to Sydney. "We wanted to be closer to Undila," Mark says of the decision to return. "At that stage we thought we might have a chance of maintaining contact."

But they were wrong. Undila, who had a daughter in 2011, has made it clear she wants nothing to do with her family. "When you ring her she says doesn't want to talk to us," Mark says. "When you go there, her husband comes to the gate and says, 'Look, I told you, you're not allowed here. Don't come here.' The last time we went there, Rose got very emotional. She was crying. Our little granddaughter was there, and a couple of elders came up to cover the situation."

Mark and Rose now live in the Blue Mountains, with Lebana and Abraham, and are slowly putting their lives back together. Mark works in maintenance and has got back into surfing and music. He plays drums in a band called the Fabulous Shapelles and gives drum lessons at home. "I'm 53 years old, but it feels like I'm 21," he says. "It's like I'm starting over again, because you come out with nothing."

Rose works as a cleaner. "It's a bit of a disappointment to my family," she says. "I don't want to spend my life being a cleaner."

She has read about mind control, trying to come to terms with her experience. "When I look back, I can't believe it all happened. It's so bizarre. It's like I became a completely different person."

In the cult, she notes, they decide who has the right to exist and who does not. "But here we are," she says. "We still exist. That's something."

- The Twelve Tribes was approached by Good Weekend, but declined to comment.

This article originally appeared in Good Weekend. Find Good Weekend on facebook at facebook.com/GoodWeekendMagazine