QUOTE(Morgan25 @ Oct 19 2006, 11:30 AM)

Isn't one of the main ones called the Unification Church? It's funny how weird offshoots of Christianity started in East Asia... Like Jesus' younger brother in China

Maybe it's because Western Christians were largely kept out and in some cases killed when Christianity started gaining a little ground there?
The UC ("Moonies") has been in Korea for many, many years. When I first lived in Korea twenty-three years ago, there was one of their "churches" located a couple blocks from my house. There are many Christian cults, just as strange and some stranger, that have taken root in the past several years.
As for early Christianity in Korea, timing is everything. When the first protestant missionaries came to Korea, at the end of the 19th C., Korea was in transition from a failing monarchy to a colonized society. Those Western missionaries came as doctors, engineers, teachers, etc. and provided needed services. In the beginning, proselytizing was forbidden, but as King Kojong's private physician and other advisors were missionaries, the rules were somewhat unenforced. Christianity took off and, with the exception of some slow down due to wars and such, really hasn't stopped since.
In my experience, when Koreans take hold of some idea, it becomes assimilated into the culture and is soon uniquely Korean. Religion and philosophy are good examples of that.