SEOUL, South Korea >> At meetings of the secretive Shincheonji Church of Jesus, worshippers sit packed together on the floor, forbidden to wear glasses — or face masks. They come to church even when sick, former members say. After services, they split up into groups for Bible study, or to go out into the streets and proselytize.

After the first coronavirus infection was reported among its members, they were told to lie about being followers, though the church later said that was not its policy.

Now, health officials are zeroing in on the church’s practices as they seek to contain South Korea’s alarming coronavirus outbreak, in which members of Shincheonji along with their relatives and others who got the virus from them, account for more than half of the confirmed infections. On Saturday, the number of cases in the country soared to 346 — second only to mainland China, if the outbreak on the Diamond Princess cruise ship is excluded from Japan’s count.

More than 1,250 other church members have reported potential symptoms, health officials said, raising the possibility that the nation’s caseload could soon skyrocket further. In response, the government is shutting down thousands of day-care facilities, nursing homes and community centers, even banning the outdoor political rallies that are a feature of life in downtown Seoul.

As of Saturday, more than 700 members of Shincheonji, which mainstream South Korean churches consider a cult, still could not be reached, according to health officials, who were frantically hoping to screen them for signs of infection.

“Shincheonji members know of their bad image and they usually hide their affiliation from nonchurch members, even from their parents,” said Hwang Eui-jong, a pastor who has researched the church. “No wonder many of them are unreachable. They must be huddled together somewhere, praying that this will eventually go away.”

The snowballing outbreak among the church’s followers is testing South Korea’s health care system, which successfully tamed a deadly outbreak of Middle East respiratory syndrome in 2015. Experts on South Korean religious sects and former members of the church said its practices made its members unusually vulnerable to contagious diseases.

“Unlike other churches, Shincheonji makes its members sit on the floor tightly together during services, in neat, militarylike ranks and files,” said Lee Ho-Yeon, who left the church in 2015. “We were not supposed to have anything on our faces, like glasses or masks. We were trained to sing our hymns loudly.

“We were taught not to be afraid of illness,” Lee said. “We were taught not to care about such worldly things like jobs, ambition or passion. Everything was focused on proselytizing, even when we were sick.”

The outbreak has struck hardest at Shincheonji’s church in Daegu, a city of about 2.5 million in the country’s southeast, where a 61-year-old woman known as Patient No. 31 is believed to be a link between many of the cases. The restrictions on public gatherings have been implemented more forcefully in Daegu than elsewhere in the country.

Patient No. 31 checked into a small Daegu hospital on Feb. 7, after a minor traffic accident. The next day, she complained of a sore throat. The day after that — a Sunday — she attended a Shincheonji church service, health officials say.

She developed a fever the next day, one that lingered, and she stayed in the hospital. Still, she slipped out the following Sunday to go to church again. At least 1,000 Shincheonji members attended one of those two Sunday services, officials said.

At least twice, doctors recommended that the woman transfer to a bigger hospital to be tested for the coronavirus, but she refused, health officials said. She insisted that she had not visited China in recent months, nor had she met anyone known to have the virus.

Finally, on Monday, she felt sick enough to check into a government-run clinic for a coronavirus test. On Tuesday, she was confirmed to be infected.

“Her behavior is not surprising to people familiar with the church,” said Chung Yun-Seok, an expert on religious cults who runs the website Christian Portal News. “To them, getting sick is a sin because it prevents them from doing God’s work.”

The church dismissed criticism of its practices on Friday, calling it “slandering based on the prejudices among the established churches.” It said its members sat close together on the floor because local authorities would not give it permits to build bigger churches.

Health officials were still trying to figure out how Patient No. 31 contracted the disease. Hwang noted that the church had been proselytizing among ethnic Koreans in northeastern China, many of whom it invited to South Korea.

Jung Eun-Kyeong, director of the Korea Centers for Disease Control and Prevention, said authorities were investigating reports that Shincheonji had operations in Hubei, the Chinese province that includes Wuhan, where the virus emerged. The South Korean news agency Newsis reported on Friday that Shincheonji had opened a church in Wuhan last year, and that references to it had been removed from the church’s website. Church officials could not immediately be reached for comment.

South Korean officials learned that Patient No. 31 had visited Cheongdo, a county near Daegu, in early February. As of Saturday, 108 patients and medical staff at a Cheongdo hospital had tested positive for the coronavirus; two of them died this week.

Cheongdo is the birthplace of Lee Man-Hee, the 88-year-old self-styled messiah who founded Shincheonji, and followers regularly go on pilgrimages there and do volunteer work. Church members are also believed to have attended the funeral of Lee’s brother in Cheongdo in early February.

On Friday, Newsis quoted Patient No. 31 as saying that she had not visited the hospital or attended the funeral, but that she had used a public bathhouse while in Cheongdo.

“We need a thorough investigation of the people who attended the church services and the funeral,” President Moon Jae-in said Friday while presiding over an emergency meeting on the outbreak.

After the case of Patient No. 31 was first reported, social media messages went out to Shincheonji members telling them to continue their evangelical work in small groups. The messages also told members that if officials asked, they should deny that they belonged to the church or went to its services.

But the church later said those messages did not reflect its official policy, and that it had disciplined the person who sent them out.

On Friday, Lee urged his members to “follow the government’s instructions,” asking them to avoid gatherings and take their proselytizing online.

“This disease outbreak is the work of the devil, which is hellbent on stopping the rapid growth of the Shincheonji,” he said in a message to his followers.

South Korea has long been fertile ground for unorthodox religious groups, some of which have amassed enormous wealth and influence. After an overloaded ferry sank in 2014, killing more than 300 people, South Koreans were shocked to learn that the ferry company was controlled by a religious leader who had been shunned as a heretic by mainstream churches.

Shincheonji claims 150,000 members and has 12 congregations in South Korea. It also has many smaller operations, which present themselves as cafes or churches of other denominations and are used for proselytizing, Chung said.

Shincheonji has long been criticized for its aggressive evangelical work. Many mainstream churches post signs warning undercover Shincheonji missionaries not to try to infiltrate their congregations.

Members of Shincheonji have recently targeted young South Koreans, offering them free tarot readings, personality tests and foreign-language classes, according to Hwang.

Moon Yoo-ja, 60, who spent years trying to “rescue” her daughter from the church, accused Shincheonji of ruining many families.

“Once they fall into the trap of the church, they often abandon school and jobs,” Moon said. “Some housewives packed up and joined the church, abandoning their husbands and children.”

Hwang Gui-hag, editor-in-chief of the Seoul-based Law Times, which specializes in religious news, cautioned against focusing too much on Shincheonji’s practices, some of which he said could be found in other South Korean churches.

“This is essentially not a religious issue, but a medical and health issue,” he said. “If we pay too much attention to religion, we miss the point. How would you explain the huge outbreak in Wuhan, China, which is not really caused by any church?”

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