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 convicted of murder over the attack on May 28, 2014 -- 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.
And on Monday, two of them -- father and daughter duo Zhang Lidong and Zhang Fan -- were executed in east China's Shandong Province on following the approval of the use of the death penalty by the Supreme People's Court.
After his arrest last year, state television broadcast 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.