Seoul, South Korea (CNN) Standing in front of her parish in a bright yellow jacket, Shin Ok-joo holds back tears. Her voice takes on a tone of both anger and sadness.

"How could you behave like this?" she asks her congregation in a video purportedly filmed in South Korea in April last year at the Grace Road Church, where Shin serves as pastor. Soft weeping from people seated in pews intensifies into a chorus of sobs. "Am I your toy? Did I tell you I was your toy? You crazy one!"

Shin leaves her pulpit but remains on the raised platform above her congregation as she approaches a group of people with their heads bowed. With her left hand, she grabs a worshiper in a brown coat by her hair and, with her free hand, slaps the person across the face. The slaps continue, and the crying from the audience grows louder. Shin's emotion is apparent on her face.

After four slaps, the congregant falls to the floor. Shin picks up the woman by the hair and shakes her head violently. By this point, the audience's screams are loud, raw and visceral. Shin yells at her, but what she says is inaudible due to the sobbing.

According to Grace Road, this is an example of what the church calls "threshing," a ritual involving church members being slapped and hit as a form of repentance in accordance with Shin's interpretation of the Bible. It symbolizes separating sin from the human body in the same way that grains are removed from crops by threshing.

The woman at the receiving end of Shin's blows had just returned from Fiji, where about 400 members of the church have moved to set up shop. Shin preaches that Fiji is the land chosen by God to be the center of the world and the ideal place to survive an impending great famine, and the church has made significant investments in the country.

Video of this incident was supplied to CNN by Daniel Kim, Shin's son, in an attempt to counter allegations from former congregants of violence against its members.

The footage from Kim was sent a day after three former members of the church revealed 20 minutes worth of footage of particularly violent threshing incidents at a news conference in Seoul Wednesday.

"Shin is a cult leader and the Grace Road Church is a cult," Lee Soon-deok, one of the former members, told the media Wednesday.

"She tells people that she is the only one to rely on, that people can only be saved by her. Shin is an evil woman."

Former church members contend that the threshing ritual is assault -- and South Korean prosecutors have moved to punish Shin for it. She was arrested in July and remains behind bars awaiting trial, charged with forced confinement and physical assault. At the time of Shin's arrest, South Korean authorities said many of congregants in Fiji appeared to have been stripped of their passports upon arrival by senior members of the church.

From left to right: Lee Soon-deok, Park Chan-moon and Lee Yoon-jae, former members of the Grace Road Church, speak at a news conference Wednesday. The banner above them reads "Please rescue 400 South Koreans in Fiji!"

But Kim is vigorously fighting that narrative, denying allegations that the church treats its parishioners like modern-day slaves. He accused the parishioners who left Grace Road and South Korean media of slandering the church, and said the allegation that the 400 members of Grace Road are subjected to forced labor was "insane."

"They don't know what is really going on here," Kim said.

He said threshing does not constitute a crime because it is done by consent and claims the footage revealed last week was maliciously edited. To offer better context surrounding the ritual, Kim supplied CNN with the church's video of the April 2017 incident along with nearly 13 hours of footage spanning two years, on the condition that CNN not reproduce or redistribute the images.

The footage sent by Grace Road to CNN shows the threshing as part of Shin's sermons. The parishioners do not appear to be hit against their will. But the incidents are physical, at times violent, and hard to watch.

"She tells people that she is the only one to rely on, that people can only saved by her. Shin is an evil woman." Lee Soon-deok, former Grace Road Church member

Originating in South Korea, a country notorious for its extreme religious movements, the Grace Road case has raised a series of questions about what constitutes consent when one adult wields significant spiritual and mental influence over another, to the point where someone thinks their immortal soul is at risk if they don't follow their leader's teachings. And it appears to show the power of herd mentality.

"It may be difficult to understand for others but Shin destroys emotions and love among family members," said Song, a church defector who agreed to speak to CNN using a pseudonym in order to protect her from reprisals.

"The church system trains people not to feel sorry for their friends or family when they get punished. People are brainwashed to think it was the evil spirit inside people (being beaten out) so they don't need to feel sorry."

The April incident from last year -- in the video provided by Kim -- is a telling example. After Shin finishes slapping the first woman, another worshiper in an off-white shirt approaches Shin from below the platform she is standing on. The congregant hugs her at the waist, looking up as the child does to a mother. Shin slaps the individual twice, but with less power than the previous person. What was a light embrace then turns into a full-on hug, and the pair weep in each other's arms.

Nearly a dozen congregants follow, and for the next 10-plus minutes, they hold each other, and the wailing reaches fever pitch.

Grace Road said in an email that the incident started because Shin "was so deeply saddened by the some of our members (sic) who still could not believe nor understand, even though the Bible was interpreted with the Bible, and the mysteries that were hidden in the Bible were revealed to them perfectly. So our Reverend called out those who came back from Fiji to the front and rebuked them.

"The woman in the brown coat at the start went to Fiji and came back, and she was rebuked because she was still so immature, and she just could not understand, and our Reverend could not turn a blind eye to her. Even apart from this woman, our Reverend rebuked the others for not properly understanding the Word of God and as a result, acting arrogantly and doing whatever they want to, and for having quarrels with each other."

The crying, the church says, was because Shin could not take the entire parish to Fiji if they all "don't act according to the Word (of God)."

Members of the church in Fiji are free to move and travel as they so choose, according to Kim.

'They're telling a story'

Grace Road first established a base in Fiji in 2014, after Shin predicted there would be a great famine and that the island nation was the ideal place to survive it and prepare for the second coming of Jesus.

They call it a world where "only God is God."

According to its website, the Grace Road Church and its corporate affiliate, the Grace Road Group (which is sometimes referred to as GR Group), began their work in Fiji investing in agricultural industries.

"GR Group is a group of Christians who see, hear, believe, and act by the Bible. We listened to the Words of God though our reverend, gathered from all over the world, and moved to Fiji for the God-given vision. We believe that Fiji is the promised land hidden in the Bible, beautiful and pristine land blessed by God. We came to make Fiji the light of the world by making the Words of God come true," the company said.

Grace Road Group has grown significantly in scope in the last four years, operating some 50 businesses in the restaurant industry, retail, construction and farming. Grace Road Church's 400 parishioners are employees of the Grace Road Group, Kim said. The company also employs around 200 Fijians, Kim told CNN.

These jobs and investments are in a country with one of the world's smallest GDPs that is trying to attract more foreign investors.

Grace Road Group's business ventures have been lauded by Fiji's highest levels of government. Pictures in local media and on the GR Group website show Prime Minister Josaia Voreqe Bainimarama personally appearing beside GR Group's president to give the company an award for its business successes in 2017. A tweet from the group that administers the awards has since been deleted after CNN's first report on Grace Road.

Kim explained to CNN that although he is the GR Group president, the church's members all co-own the business. He said that none are being kept against their will and they are free to come and go as they please. Of the nearly 600 who have made the move to Fiji, about 200 have left of their own accord, Kim said.

Some who have left the church, on the other hand, say they were subjected to "14 hours of heavy daily labor, surveillance, punishments and a group assault."

Kim said members of the media are welcome to visit to Fiji to "find the truth."

Several Korean broadcasters have traveled there to produce documentaries on the church, which Kim accused of being one-sided.

"We are frustrated," Kim said. "They're not telling the truth -- they're telling a story, an exciting story."

Kim said he and many members of the church have been questioned by what he called a "full investigative team," involving about 20 officials from the South Korean government, Interpol and Fijian police two months ago. The company and church today are still operating as normal, he said, albeit without their leader.

The former parishioners speaking out allege collusion between the church and the Fijian government for them to be able to thrive in Fiji. Kim denies any links with Fijian authorities, and says his businesses are operating legally.

"We are frustrated ... They're not telling the truth -- they're telling a story, an exciting story." Daniel Kim, Grace Road Group president

South Korean police refused to give specific details about the process of their investigation, but said they have issued seven Interpol red notices -- a request from one country to another to arrest an individual.

Authorities in Fiji have been tight-lipped about the case.

Shortly after Shin's arrest, the country's attorney general, Aiyaz Sayed-Khaiyum, said the incident would not affect GR Group's business interests.

"We have not had any repercussions on any of the projects they are currently undertaking as the same way as the shops are all running, patisseries and food outlets are all running," Sayed-Khaiyum said in August, according to The Fiji Times

Media representatives for Fiji's police, attorney general and Ministry of Employment have not responded to multiple requests from CNN seeking comment.

'Our ultimate destination'

Hwang, a former Grace Road Church member who wished to go only by his surname out of fear of reprisals, told CNN that he left for Fiji at 17.

When he first joined the church in South Korea, he said he went there every Sunday. After one year, he was going every day and eventually counted himself lucky that he was chosen to go to Fiji.

"For years, Pastor Shin Ok-joo preached to us about how Fiji would be our ultimate destination," Hwang said. "We believed that only the select few could go there, so when she told me and several others to go, I couldn't say no."

A man surnamed Hwang, a former Grace Road Church member, is seen looking out a window after speaking with CNN. CNN has agreed not to reveal his full identity due to fear of reprisals.

Song, the other defector, explained to CNN how the so-called "threshing" was part of Shin's preaching, but eventually transformed from a voluntary exercise to something more mandatory.

"I remember the day when the threshing floor routine began," said Song.

She explains how, on the first day, a man "came forward and confessed that he had committed an adultery and how shameful he was. He also said in front of the crowd that he deserved to die. Then pastor Shin slapped (the man's) face a few times but it wasn't hard. It seemed more of a symbolic gesture than a punishment at that time," Song said.

"Another leader level person, came forward and said that he also had an affair. People were moved by these two people talking so frankly about their behaviors. More and more people came forward and began telling their stories and asked pastor Shin to punish them as well," she said.

"However, the process changed later. Instead of people voluntarily coming forward to confess their wrongdoings, Shin pointed out people's misbehaviors and they had to be beaten."

Song said she was subjected to her first threshing session in front of 350 people.

"It was like standing in a public trial," Song said.

"Shin said that I wasn't even a human but animal. She called my name and began hitting my face while grabbing me by my hair. I began bleeding in the nose and several men came out and grabbed my legs and arms. Women began cutting my hair. I don't know how much time had passed. Maybe it lasted about three hours," said Song.

The 20 minutes of video shared by trio who left the church during their Wednesday news conference appears to show some similar incidents, including one that involves children. Shin does not appear in the video showing violence against children.

One grainy clip shows Shin slapping members of the church as she tells them, "This won't kill you. You're bleeding but you're not going to die." It also shows children sitting in a circle, some being slapped and kicked.

Another video shows a mother and daughter being encouraged to slap each other. After the daughter slaps the mother, the mother can be heard sobbing while she slaps her daughter across the face, switching sides as she does so. Multiple former church members said some videos were filmed in order to prove to Shin that the threshing sessions took place.

Kim said the videos showing children being hit were not sanctioned by the church or by Shin; the group does not condone the "threshing" of minors; and any videos showing children being hit constituted an abuse of authority by members of the church. He did not send CNN raw footage of any incidents involving children. When asked about the other incidents that did not involve minors, Kim did not deny that they took place, but said the videos are misleading and edited.

Former members of the church disagree, saying these rituals "destroyed love among family members."

"These 400 people are exposed to unspeakable pain as well as antisocial and immoral behaviors," they said.