Paul Yoo at first thought the text was a joke, or perhaps spam. "Chinese secrets are like the heavens and the big mountains. Do not reveal or talk about them," read the cryptic message.
It sounded like a poem, although not one Mr. Yoo or his friends had ever heard of. He was prepared to laugh it off, until he discovered that no one else had received the same message.
"That's when I realized something was going to happen," he said.
A week later, police arrived at his door in the northeastern Chinese city where Mr. Yoo, a South Korean missionary, had lived untroubled by authorities for years in a country where proselytizing by foreigners is, officially, illegal.
China is turning a blind eye no longer. The knock on Mr. Yoo's door two years ago marked the beginning of a quiet forced evacuation of foreign missionaries, including hundreds of South Koreans, some of whom have worked to train and convert Chinese, and others who have helped Christian defectors from North Korea.
Those who remain live in mounting fear that they will be next, as China's new president Xi Jinping seeks to rid the country of foreign influences and effectively nationalize Christian churches to bring them under state control.
"This crackdown, and the people being deported, has intensified starting from May," said Rev. Peter Jung, director of Justice For North Korea, which supports North Korean defectors. And, he said, "the number of missionaries getting arrested has increased."
The eviction of missionaries is in some ways a mark of China's own perceived global strength, as an increasingly confident Beijing seeks to define China, an atheist state with government-run churches, on its own terms. Yet it also threatens to revive a point of conflict between China and Western nations, which have long criticized the Communist country for its refusal to allow free pursuit of religion.
Conditions in China have never been easy for foreign missionaries, and most try to keep a low profile. They work for so many different organizations and denominations that numbers are hard to come by. But from interviews with nearly a dozen former and active missionaries, experts and academics it's clear at least hundreds – perhaps nearly 1,000 – have been forced out of China. In early 2013, at the peak, China was home to some 2,000 to 4,000 missionaries from South Korea alone; U.S. missionaries made up large numbers as well.
The forced departures form the background to the detention a little more than two weeks ago of Kevin and Julia Garratt, a Canadian Christian couple who had run a coffee shop in Dandong, a Chinese city on the North Korean border. Chinese authorities have accused them of stealing state secrets, but said little about what they have done wrong. Canadian officials believe their detention is likely China's response to allegations of Chinese espionage in North America, including by a Canadian immigrant who is accused of co-ordinating hacking attacks to steal U.S. fighter jet secrets.
Yet the Garratts also stood at a dangerous nexus of issues that stir Chinese suspicion, by virtue of their personal faith, their humanitarian work with North Korea and the donations from Canadian churchgoers that supported them. That background almost certainly attracted the attention of authorities, though it may not be the primary reason for the couple's detention.
'It's extremely sensitive'
China is North Korea's closest ally, but the two nuclear powers still operate with great of mutual suspicion, and the Garratts live in a place that is the focus of intense Chinese military and intelligence scrutiny. Some of that is directed at Christian missionaries who play a critical role in the underground railroad that secrets North Korean defectors out of China.
"If you are a North Korean in China, the only place where you can realistically be given food and shelter is a church," said Andrei Lankov, a Russian scholar and expert on North Korea. Often, that means the involvement of missionaries, who "actively proselytize among the North Korean refugees," and train them in spreading Christianity inside North Korea.
The Chinese pressure on missionaries, however, extends far beyond the North Korean border, suggesting Beijing's chief motivation is concern about religion.
"One of the aims of Xi Jinping's policies is to get rid of all missionaries by 2017," said one missionary who continues to work in north-eastern China.
Such a claim is impossible to verify. Mr. Xi, the Chinese president, has publicly said no such thing. But fears in the missionary community of a coming clean sweep offer a window into the degree of alarm that has spread. The missionary asked The Globe to reveal no potentially identifying details, including his age or nationality, how much time he and his wife have spent in China or the nature of their work there.
"It's extremely sensitive. A tiny little clue could identify us and get us kicked out," said the missionary's wife, who travels to China separately from her husband in case one of them is detained.
Mr. Xi's presidency has already coincided with powerful new campaigns to curb groups that could challenge the power of the Communist Party. Human-rights lawyers have been jailed and mercilessly tortured. (Last week, one lawyer, Gao Zhisheng, was released from prison mentally "utterly destroyed. He can barely talk," activists said.) Bloggers have been threatened with strict new punishment for "spreading rumours."
Underground churches, which Beijing sees as co-ordinated groups with the potential to organize political resistance, have been torn down. And missionaries, who represent a direct foreign influence on Chinese citizens, have been ejected.
The departures have happened quietly, often mandated by authorities who refuse to renew visas, a tactic also used to kick out journalists. Some missionaries accustomed to one-year stays are now being offered three-month visas that place them in constant uncertainty.
'Government wants control'
Many, like Mr. Yoo, face probing and uncomfortable questions. The police officers who questioned him at his home wanted to know what he did every day, the source of his income, what he had done in South Korea before he came to China and how he was educating his children.
He said he avoided referring to "church" in his answers but had no doubt that authorities knew the truth. Months later, he took his wife and two children to Canada in hopes things would cool down.
Earlier this month, they headed back to Seoul where they hoped to secure a new Chinese visa. Their flight took them through China, but they had new passports, with fresh numbers and pages clear of evidence they had been in the country before.
It didn't matter. Their names raised flags at immigration and the entire family was sent into a side room for questioning. Mr. Yoo and his wife were ordered to sit for mug-shot style photographs. Then, shortly before their plane to Seoul departed, they were released. An officer accompanied them to the door of the aircraft.
It was never said outright, but they were left certain they were no longer welcome in China. "When they were taking pictures like I was a criminal, I felt I was being deported, for sure," Mr. Yoo said in Seoul, where he is now living with parents, without a home and unsure of what his future holds.
Mr. Yoo decided to be a missionary when he was barely out of high school. "I get so excited just breathing the air in China and meeting people there," he said.
He cried as his plane took off the last time from Beijing.
"I started praying, 'God, please forgive China. This is a land that needs healing. Christian work needs to be done.'"
China has said little about what is happening with its Christians. The State Administration for Religious Affairs and the country's Foreign Ministry did not respond to faxed requests for comment. In May, Foreign Ministry spokesman Hong Lei, in one of the few official Chinese statements, said "the Chinese government earnestly protects the rights of Chinese citizens including safeguarding their freedom of religious beliefs."
In South Korea, a former missionary who asked to be called Brother Paul said he believes China is evicting missionaries amid a renewed campaign to require Chinese Christians to worship only in government-run churches. Those churches can be useful to Beijing in doing the state's job, easing social tensions and solving social inequalities through good works.
China wants its religious people "registered, because government wants control," Brother Paul said. He asked that his full name not be used because he has, for a decade, met regularly with Chinese authorities who have studied the role Christians have played in shaping South Korea. Of China's estimated 50 million to 100 million Christians, only 21 million attend official churches.
In an interview, Bishop John Fang Xingyao, chairman of the Chinese Catholic Patriotic Association – a state-sanctioned organization – described the official view of the church. It is a vision of Christianity as an organ of the Communist Party, not the haven of spirituality sought by missionaries and the underground churches with which they work.
Church, Mr. Fang said, "plays a role in maintaining social stability," he said. "Generally speaking, the crime rate among believers is much less than among non-believers."