Hong Kong (CNN) -- The group was approaching fellow diners at a McDonald's restaurant in an eastern Chinese city on a recent Wednesday night, asking for their cellphone numbers, when one woman refused.
What happened next, captured by terrified onlookers on their cellphone cameras and later replayed in news reports, would shock the Chinese public and trigger an official crackdown on what Beijing has characterized as a dangerous doomsday "cult."
"Go to hell, demon," one of the accused, Zhang Lidong, yelled as he beat the woman with a steel mop handle, telling her she would "never come back in the next reincarnation."
Other members of the group threatened diners that they would kill anyone who intervened, reported Chinese state media.
By the time police arrived at the fast food outlet in the city of Zhaoyuan, in the eastern Chinese province of Shandong, they found the victim, a 37-year-old mother named Wu Shuoyan, lying in a pool of blood.
Zhang was kicking and stomping her while a boy beat her with the mop handle, state media reported; within the hour, she was pronounced dead at a local hospital.
Five adults have been charged, along with a minor, with murder over the May 28 attack -- Zhang Lidong, Zhang Fan, Lyu Yingchun, Zhang Hang, Zhang Qiaolian. They are all members of the Church of Almighty God ("Quannengshen"), Zhaoyuan police said in a statement.
State television subsequently broadcast an interview with Zhang Lidong in his cell, in which he confessed to the killing but expressed no remorse.
"She was a demon," he said, telling the interviewer that he and his co-accused were members of the church. "She was an evil spirit."
Authorities said the accused were likely gathering the phone numbers to find potential new recruits when Wu's refusal angered them, state media reported.
Struggle with the 'great red dragon'
Also known as Eastern Lightning ("Dongfang Shandian"), the group preaches that Christ has been reincarnated as a woman from central China, and that the righteous are engaged in an apocalyptic struggle against China's Communist Party -- which they refer to as the "great red dragon."
Linked to kidnappings, violence and extortion, the group has been listed among 14 banned religious groups by China's Ministry of Public Security since 1995.
Emily Dunn, an Asian studies academic at the University of Melbourne who wrote her doctoral thesis on the group, said its illegal status had made it paranoid and secretive, with members often only knowing each other by aliases, so they could not incriminate each other if detained by authorities.
"It's about as illegal and politically sensitive as religion gets in China," she said. "As the government has cracked down more, Eastern Lightning's rhetoric has escalated against the government."
China's Academy of Social Sciences says there are now 23 million Christians in the country. But with many belonging to non-sanctioned, underground "house churches," experts believe the true number of Chinese Christians could be much higher.
Eastern Lightning, part of a tradition of heterodox, quasi-Christian religious movements in China, was estimated as having between several hundred thousand and one million members, said Dunn. It was viewed by Beijing as the most serious threat to public stability of any of the Christian-affiliated movements that have been growing rapidly as China undergoes a religious revival, she said.
"There have been reports of murders and beatings at the hands of the group, but also at a more general level, very aggressive proselytizing, harassment, brainwashing," said Dunn. "Those accusations are very routine."
An 'evil cult'?
Chinese police have released material to Christian pastors warning of the group's activities. In one video, it describes the group as "a classic example of an evil cult that takes the name of a fake religion to carry out actions harmful to others."
It accused the group of spreading lies, scamming money, endangering lives, deceiving the public, attacking the government and undermining social stability.
Members of the Church of Almighty God who operate the group's English-language website responded to a request for comment from CNN, stipulating in an emailed reply that "our church doesn't exactly have a spokesperson because nobody can fully represent" the group.
The response stated that it was "very natural" for the Chinese government to blame the killing in Zhaoyuan on the group, as it was the "stock-in-trade" of the Chinese Communist Party to slander then suppress those that disagreed with it. The statement argued that the Tiananman Square massacre, Tibet and the suppression of the banned Falun Gong religious movement are examples of such a pattern.
"They always find some excuse in advance and fabricate things and slander them," said the statement. "Then they draw up some rumors as the basis for their attack and make false charges, and then they carry out their bloody suppression."
The group -- which believes that Christ has returned and began his work in China in 1992, and that only those who accepted his "end-time work" would be saved -- had been persecuted since its inception, read the statement.
It concluded what the group said were the words of "the end-time Christ":
"God does not participate in human politics, but God controls the destiny of every nation and race," read the statement.
"We all believe that the thing God will accomplish cannot be hindered by any nation or any force, and that those who obstruct God's work, resist God's word, and disturb and damage God's plan will eventually be punished by God. If a man resists God's work, God will cast this man into hell; if a nation resists God's work, God will destroy this nation."
A female Christ?
Eastern Lightning was founded in the early 1990s by Zhao Weishan, a physics teacher with a history of membership of radical quasi-Christian sects, who preached about a female Christ figure hailing from China, said Dunn.
The group's moniker was drawn from a verse in the New Testament: "For as the lightning cometh out of the east, and shineth even unto the west; so shall also the coming of the Son of man be".
In a video produced by Chinese police warning about the group, it is claimed that Zhao first became a member of a radical religious movement, known as the Shouters, in 1987. It said he honed his expertise at religious "scams" there, before branching off in 1989 with a movement, based in Heilongjiang Province, elevating himself as the object of veneration.
When the group was broken up by authorities, said the video, Zhao abandoned his family and fled to Shandong and Henan provinces. He teamed up with a woman 20 years his junior, and began preaching that she was the Female Christ, with himself as the new movement's high priest, according to the video.
The police referred to the woman as Yang Xiangbin; Dunn said she was also known to followers as "Lightning" Deng, although the group had released statements online denying this was the case.
"But they don't say whether she's still alive or where she is or what her name is," she said. "They don't tell you anything but that she was a middle-aged woman who was inspired by God and God spoke to her, so she started speaking God's word."
The police video said Zhao fled to the United States in 2000.
Kidnappings, assaults alleged
The sensational nature of Wu's killing triggered an outpouring of revulsion towards the group in Chinese social media. But it is not the first time the movement has been in the spotlight.
In December 2012, Chinese authorities rounded up hundreds of Eastern Lightning members when the group proclaimed, via loud public protests, that the end of the world was imminent.
The state-run China Daily reported that in October and November 1998, the group was responsible for a spate of robberies and assaults in China's central Henan Province that left victims' limbs broken and ears cut off.
And in 2002, the group allegedly kidnapped 34 evangelical Christian leaders belonging to the China Gospel Fellowship by posing as representatives of a theological institute from Singapore, holding them for two months in an effort to convert them, said Dunn.
The kidnapping episode reflected a longstanding strategy from Eastern Lightning to try to co-opt entire congregations -- whether underground "house churches," or state-sanctioned Protestant and Catholic churches -- by converting their leaders, she said.
To this end, they were said to use tactics including seducing, extorting or threatening pastors.
But most Eastern Lightning converts were middle-aged Christian women, said Dunn, with many hailing from impoverished rural areas, although the movement seemed to be increasingly penetrating wealthier urban areas. The group appealed to potential recruits through a promise of saving them from impending disaster or fatal disease, and had a reputation for strong-arm tactics.
"People are encouraged to door-knock, to pressure everyone they know to join the group. They send out evangelists throughout China," she said. "Their message is that if you don't join, you're more likely to go to hell or perhaps drop dead from cancer or God's judgment in some other form."
A foothold in Hong Kong
Kevin Yeung is the general-secretary of Hong Kong's Concern Group on Newly Emerged Religions, an organization formed by various evangelical Christian churches in the Chinese territory to monitor the growth of new religions, provide public information about the groups and assist those looking to leave.
Affiliated churches report to the group when members of their congregations are approached by or defect to cult-like new religious movements, he said.
He told CNN his group had been monitoring Eastern Lightning since 2008, but had noted an increasingly aggressive push by the group to convert Christians in the territory over the past two years.
He estimated Eastern Lightning had approached members of about 500 churches in Hong Kong, and won about 2,000 converts.
Their prime targets were middle-aged women from the Mainland, he said. His group had concerns about Eastern Lightning, as members typically heard reports that those who converted would often spend virtually all their waking hours with other members of the movement, damaging their ties with their families.
Dennis Balcombe, an American pastor who preaches in China for the Revival Christian Church, told CNN he had spoken to people from many churches that had "lost a lot of people to the cult."
"We don't hear of people coming out of it," he said. "It's like a mafia -- once you're in it, how do you get out?"
Balcombe said he had a run-in with the group when four members came to his office in Hong Kong one Sunday in an apparent attempt to convert him. When he accused them of being Eastern Lightning and tried to photograph them, they physically attacked him, he said, showing CNN pictures taken during the alleged assault.
Elements of the group's operation seemed like a pyramid scheme, he said.
Unfairly persecuted: Lawyer
But human rights lawyer Teng Biao, who has previously acted as defense lawyer for the banned spiritual movement Falun Gong, said the group had a right to its beliefs, and should not be persecuted by the government for subscribing to an unorthodox faith.
"A believer can be jailed for years only because he or she gives materials to other people," he said.
"It's okay to punish a criminal, that's okay. But the problem is that the government not only punishes the criminals, but the whole religious group -- even when they didn't commit any crimes."
China has a long history of disruptive quasi-Christian movements, said Dunn.
The Taiping Rebellion, a civil war in southern China which claimed over 20 million lives from 1850-1864, was a millenarian movement led by a figure who claimed to be the younger brother of Jesus. It is credited with hastening the fall of the Qing Dynasty.
Dunn said she believed Beijing's suppression of unauthorized Christian groups, or "house churches," had assisted Eastern Lightning's success, saying it made it more difficult for the faithful "to tell one underground organization talking about a Christ from another."
CNN's Zoe Li, Dayu Zhang and Serena Dong contributed to this report.