lucky severson has the story. >> there are big churches, and then there's the yoido full gospel church here in seoul, south korea. it's the mother of megachurches, with the largest congregation in the world. on a typical day, 200,000 will attend one of seven services along with another 200,000 or 300,000 watching them on tv and adjoining buildings or satellite branches. while some other churches may be losing members, this one just keeps growing. the main sanctuary here holds 21,000 worshipers packed to the rafters seven times every sunday. each service has its own orchestra, its own choir, its own pastor. there are hundreds of assistants. there need to be. each service is translated into 16 different languages for visitors. karen kim is a pastor with the church's international division. she says she was shocked when she first moved here from australia. >> i think when you've got people this size, like you have to have structure and you have to have organization because otherwise people would be getting killed. like you can't just let it all just take care of itself. like there has to