Roman Catholic missionaries did not arrive in Korea until 1794, a decade after the return of the first baptized Korean from a visit to Beijing. However, the writings of the Jesuit missionary, Matteo Ricci, who was resident at the imperial court in Beijing, had been brought to Korea from China in the seventeenth century. It appears that scholars of the Sirhak, or practical learning, school were interested in these writings. Largely because converts refused to perform Confucian ancestor rites, the government prohibited the proselytization of Christianity. Some Catholics were executed during the early nineteenth century, but the anti-Christian law was not strictly enforced. By the 1860s, there were some 17,500 Roman Catholics in the country. There followed a more rigorous persecution, in which thousands of Christians died, that continued until 1884.

Protestant missionaries entered Korea during the 1880s and, along with Catholic priests, converted a remarkable number of Koreans. Methodist and Presbyterian missionaries were especially successful. They established schools, universities, hospitals, and orphanages and played a significant role in the modernization of the country. During the Japanese colonial occupation, Christians were in the front ranks of the struggle for independence. Factors contributing to the growth of Protestantism included the degenerate state of Korean Buddhism, the efforts made by educated Christians to reconcile Christian and Confucian values (the latter being viewed as purely a social ethic rather than a religion), the encouragement of self-support and selfgovernment among members of the Korean church, and the identification of Christianity with Korean nationalism.

A large number of Christians lived in the northern part of the peninsula where Confucian influence was not as strong as in the south. Before 1948 P'yongyang was an important Christian center: one-sixth of its population of about 300,000 people were converts. Following the establishment of a communist regime in the north, however, most Christians had to flee to South Korea or face persecution.

Data as of June 1990