Seoul, South Korea - The pews of the 12,000-seat auditorium are packed for Sunday services and the capital's skyline is aglow with red neon crosses. Those not inside the Yoido Full Gospel Church - the world's largest congregation - can watch the sermons online in 16 languages.
South Korea has an ancient tradition of Buddhism, but in recent times evangelists have put Christianity on track to becoming the nation's dominant faith. Korean missionary work, second only to the United States, places it at the forefront of the global search for converts.
But the kidnapping of 23 church volunteers in Afghanistan July 19 is forcing churches to think again.
In recent years, hundreds of volunteers have been expelled from Afghanistan, Egypt and China, while others were detained or killed in Iraq. Some press ahead in Somalia, even though it was declared off-limits by the Korean government.
Two of the hostages in Afghanistan_ a clergyman and another man - have been shot to death and abandoned by the roadside. The fate of the remaining five men and 16 women, remains uncertain.
The church and the hostages' relatives say the volunteers were working on humanitarian projects and were not evangelizing.
They are mostly in their 20s and 30s, and belonged to the Presbyterian Saemmul Community Church, which has roughly 3,800 followers, in the town of Bundang just south of Seoul.
Many attended Bible school together and trained as nurses, teachers, musicians, engineers, and a hairdresser before setting off to Afghanistan on a trip headed by a pastor with the Korean Foundation for World Aid, a non-governmental agency guided by Christian beliefs.
There were 16,616 South Koreans posted in 173 countries as of January, according to the Korea World Missions Association.
The country's recent embrace of Christianity, once a tiny minority, has spurred one of the most dramatic national religious shifts in the last century. It now equals Buddhism at around 26 percent out of a population of 49 million, according to conservative estimates. The remainder have no stated religious affiliation.
Americans successfully introduced Christianity to Korea 120 years ago, but it has really gained a foothold since the 1960s, after 35 years of Japanese occupation and the 1950-1953 Korean War that left about 2 million Koreans dead.
South Korean missionary work is driven by a sense of postwar moral debt to the foreign missionaries who built schools, hospitals and orphanages. The church won further support for helping bring democracy to South Korea in the 1980s.
Christian groups also provide extensive humanitarian help to neighboring North Korea, as well as its citizens who flee into China to escape Kim Jong Il's dictatorship.
At U.S. theology centers, Korean missionaries are trained to work in potentially hostile environments by teaching culture and language rather than preaching.
"Many (Korean) ministers, theologians, and seminary professors have been educated in the U.S.," Sung-Deuk Oak, an assistant professor of Korean Christianity at UCLA, told The Associated Press. "American theology is powerful in Korea."
Cross-culture church planting, as it is known in Christian circles, has become "a worldwide trend" that is popular at Korean's dominant Presbyterian church, he said.
South Korean missionary work targets a geographical region of the northern hemisphere, known as the "10/40 window," between 10 and 40 degrees north of the equator, said Pastor Oh Sung-kwon, Secretary General of the National Council of Churches in Korea.
The area comprises roughly two-thirds of the global population - predominantly Muslim, Hindu, Buddhist, animist, Jewish or atheist - and 55 countries considered the poorest and least evangelized. Several governments there, particularly Middle Eastern Islamic nations, prohibit Christian aid work and arrest or deport missionaries.
The hostage standoff shows how badly guidelines are needed, Oh said. He feels his government is "too conservative" in assessing potential risks, but acknowledges the church made mistakes.
"It was not a mistake to help Afghans in need, but it was a mistake not to consider security. We are sorry," he said in an interview. "Church leaders are reconsidering our missionary work."
Kim He-jung, a 27-year-old attending services at the Yoido church, said she wrote a will before traveling to Kazakhstan this year on a church trip. "I have received love from God and want to share it. I am ready to sacrifice myself," she said.
Seoul is home to 11 of the world's 12 largest Christian congregations, including Yoido, which began Bible classes in a tent in 1958 and now has 800,000 members and a goal of having 5,000 churches worldwide by 2010.
It runs the Osanri Prayer Mountain retreat, where the devout can lock themselves in cubicles for prayer and fasting, and attracts a million pilgrims annually, tens of thousands of them foreigners.
South Koreans "are very hardworking and deliberate in their faith," said Amanda Thompson, who attended the Gordon-Conwell Theological Seminary in the United States with a sister of one of the slain hostages.
"They are a praying people," she said. "They have inspired me and I believe that they could do a great work of inspiration for other Christians as well - especially in America."