Around 16,000 South Koreans work in foreign countries as Christian missionaries. Only the United States of America sends more people abroad to win converts to Christianity.
Last July 23 Korean missionaries were taken hostage in Afghanistan. During an ordeal which lasted many weeks two of the hostages were killed before the others were finally released. The news put the activities of Korean missionaries around the world under the spotlight.
50 years ago in South Korea Christians made up a minute proportion of the population - now they are nearly a third. Over the same time frame South Korea's prosperity has grown, and many attribute South Korea's success to the spread of Christianity.
Ulli Schauen travels to South Korea for Crossing Continents to find out why Koreans are such fervent evangelists. He meets young recruits undergoing missionary training, and asks them about the dangers they will face abroad.
He visits Cambodia with the missionaries, investigating their "contact points" - language schools and Taekwondo clubs. What do Cambodians make of the Korean's mission? And how will Koreans react when they are confronted with a different culture?
BBC Radio 4's Crossing Continents will be broadcast on Thursday, 27 March 2008 at 1102 GMT. It will be repeated on Monday, 31 March 2008 at 2030 GMT.
Reporter: Ulli Schauen
Producer: Anna Raphael