Why Christianity is successful in South Korea and a failure in Japan seems a straightforward story. In Korea, Christian leaders became involved in the nationalist struggle against the Japanese, who occupied Korea from 1910 to 1945. Christianity thus became associated with Korean nationalism, freedom, and foreign support, and some forms of the religion even later tied in with traditional shamanism. Christian growth accelerated after the Korean War (1950–53), until by the year 2000 about 28 percent of South Koreans considered themselves Christians—about 23 percent Protestant and 5 percent Catholic.
In Japan, however, Christianity was associated with foreign interventions, especially the American occupation after the disastrous ending of World War II. The perception among the Japanese that Christianity is a religion of foreigners started when Portuguese, English, and Dutch friars and sailors brought the religion to Japan in the sixteenth century. The Tokugawa regime (1603–1868) only tolerated Christians in its early beginnings. After the Christian Shimabara Revolt of 1637–38, Christianity was prohibited and its members executed. In 1639, "under threat of destruction . . . , Iberian ships, seen as the main propagators of Christianity, were prohibited from visiting Japan. In the ensuing years only a few Christian groups survived, mainly by hiding their beliefs and practices from official eyes."