In the 19th century European visitors reported that Koreans believed the whole country was peopled with demons. Spirits were worshipped in houses, in wells and old trees, in mountains and rivers. To Isabella Bird Bishop, a Victorian traveller, writing in 1898, the spirits were "numbered in billions, and their ubiquity is an unholy travesty of the Divine Omnipresence". Shamans dealt with these spirits, claiming that illness was caused by spiritual unrest: if a man broke his leg, he had offended a spirit, if a family suffered financial difficulties, then it had not treated its household spirits or ancestors properly. Shamanism also sought to prevent misfortune by propitiating the spirits before they decided to act in a malevolent way.
At a more official level the Korean court modelled itself on China. To do this, it took on board Confucianism which, although often described as an ideology rather than a religion, encouraged the veneration of ancestors. Each clan - the Paks, Lees, Kims and so on - has an ancestral home, where it venerates founder figures, many of whom lived 1,000 years ago. Confucianism became the state religion at the beginning of the Choson dynasty (1392-1910), when Buddhism was outlawed. Buddhism had been the dominant religion up to that time. Monks were exiled to mountains, where they tended vegetable plots and begged for alms. They denied the reality of earthly life and believed that only those who learnt to control physical desire could achieve salvation by escaping the cycle of birth, ageing, sickness and death.
Buddhism played a big part in Korea's artistic expression until the 14th century, so many of today's prized sculptures, buildings and archaeological treasures are Buddhist in inspiration or imagery. The religion also enjoyed a revival in the early 20th century. Today, slightly more Koreans claim to be Buddhist than Christian.
Confucianism is all about hierarchy and group identity, while Buddhism and shamanism search for peace and order in the cosmos. Christianity challenged these ideals, preaching the rights of man and promoting the idea of personal salvation. It denied the importance of ancestors and the reality of shamanistic spirits. In the 19th century it was considered a threat to social stability and Christians were persecuted. In 1984, 103 martyrs from that time were canonised when Pope John Paul II visited Korea.
Nowadays it is Christianity that has had to adjust. Christians routinely visit family graves and pray in an echo of Confucian ancestral veneration. Many Christians pray for blessings, much as used to happen when they visited shamans. There are also many "new religions" that mix Christianity with the old, the most famous of which is the Unification Church of Sun Myung Moon.