This fact has been puzzling me for many years--many Koreans I know are Christians--but why?
Christian, surpassing other religions, is now the dominating religion in Korea; more than 70% Koreans are Christians and the number is rapidly increasing. Considering Korea is a Asia country and Christian was never one of traditional Asia religions, this fact becomes a surprise.
One has to look into history for answers. In geology, Korea is a small country between China and Japan. In history, invadesions from Japan and from China have never been stopped. Along with invades, both Chinese and Japanese cultures influenced Korea heavily. After World War II, Korea wanted to be independent from China and from Japan especially in culture. Having a 'national religion' that is different from Chinese's Buddhism and from Japanese's Shintoism became urgent. Christian is the result of that decision.
Normally, people tend to regard personal religion choices as private matters. In fact, it is not true. From the example above, we see that how a national policy could drive a personal decision. To be a truly independent person is not easy. One has to be both brave and wise to cope with peer pressures.