This is a link to an article someone wrote about the the rise and power of Christianity in this S. Korea. I can attest to just about everything she says.
In Korea, life seems to be all about making connections that will somehow better your position and help you. People you haven’t spoken to in years will suddenly call you and ask you for favors. So it makes sense that the congregations get so big. And let’s not forget that being a pastor is like a job and a church being like an office building. I had the luxury of having a man tout that he was a dentist and continuously ask me to come visit his flat, but then after he gave me his business card, found that on the other side, he was also a pastor.
I really don’t know what to think of religion in Korea but as I said before, this article describes it very well. Take a look.