By Charles Scanlon
BBC correspondent in Seoul
Religious fervour is a hallmark of Korean Christianity
South Korean Christian missionaries have begun targeting the Muslim world in an effort to win converts from Islam.
South Korean churches - whose work was highlighted recently by the kidnapping of South Korean missionaries in Iraq - say they have a sacred duty to spread their faith in the Middle East, despite the dangers.
In a scene of religious ecstasy on a weekday morning, 10,000 people have packed into the Yoido Full Gospel Church for a regular service.
The fervour is a hallmark of Korean Christianity.
After explosive growth at home - local churches are now focussing on overseas expansion.
One church alone has 300 missionaries overseas - exporting their ecstatic brand of Christianity.
Altogether, there are 12,000 South Korean missionaries, some working in Muslim and communist countries which are hostile to their presence.
Pastors from various denominations are being trained for overseas assignments - and many will go to the Islamic world.
New missionaries are sent overseas each year despite kidnap dangers
Korean churches have identified Muslim countries as a new frontier.
They see it as their divine duty to spread the Christian faith.
I met one preacher who works undercover in Indonesia - where it is illegal to try to convert Muslims.
"I invited 150 Muslim children to my house on Christmas Day," he says.
"I gave them gifts and preached the gospel. But afterwards some of their parents came and threatened to kill me.
"After that I had to be more careful."
Several preachers who had gone to Iraq to set up a Christian mission were kidnapped by militiamen, but later released.
Now back with his small congregation in southern Seoul - preacher Huh Min-yong says he has no regrets.
"We must go to Iraq and the Middle East even if we become martyrs," he says.
"We must plant the cross so true peace can come. Spreading the word of Jesus can only be done with blood and sacrifice."
Target cities have also been identified across the Middle East.
Researcher Steve Moon says Korean missionaries are bold and adventurous - but they often lack cultural sensitivity.
"When they go overseas they assume it's just the same... Westerners are more sensitive and cautious," he says.
The zeal of Korean Christians knows no bounds.
About 1,000 new missionaries are sent overseas each year - undeterred by the hostility and dangers they encounter.