1. In 2007, it was estimated that over a million people with foreign citizenship were living in South Korea and the number has contiued to increase. It is not '99,98% Korean'. Also, by 2009 11% of marriages in South Korea were between a South Korean and a foreigner. About 25% of South Koreans have adopted Christianity, I doubt they consider Jesus to be Korean, so they put a different-raced deity at the top of their religious life.
1. Japan is a far better illustration of politicus's point. There are plenty of foreigners
living there but ethnic basis for
citizenship approaches (though doesn't quite reach) 100%. And Christianity's position in Japan is just weird--it's overwhelmingly considered an upper-class religion, for example.