Every Sunday, right next to the National Assembly in Seoul, a private police force shepherds people to and from the Youido Full Gospel Church. The services continue with hardly a break from morning until evening, catering for a membership that now numbers more than 700,000. It is said to be one of the biggest churches in the world.

In Japan and China, less than 1 per cent of the population is Christian, but in Korea around 30 per cent - more than 13 million people - belong to churches. The growth in Christianity has been recent - Youido was founded in a tent by the senior pastor, Paul Yonggi Cho, in 1958 - and is very much an urban phenomenon. In the Sixties and Seventies, those who came to the cities for education and work converted to Christianity, leaving their ancestral homes and extendedfamilies in the countryside behind.

Students form a large percentage of church congregations, as do people in their thirties and forties. Older generations are still tied to Confucianism, the moral and ethical code that teaches respect for authority and the veneration of ancestors, or the folk religion of shamanism, in which malevolent spirits are considered to be everywhere and in everything.

In Korea, Christianity began as the religion of the oppressed (when the Pope travelled to Korea in 1984 he elevated 103 19th-century martyrs to sainthood), but it is now a mark of modernity. In place of the hierarchy of Confucianism, Christianity preaches the rights of man, with everyone equal; in place of the shaman spiritual pantheon, Christianity believes in one, supreme God.

Every church promotes youth. Whereas the adult congregation will be divided into house groups (the Youido Full Gospel Church has 10,000 groups meeting weekly), the young are divided into age groups. These provide a full social life designed to keep young people involved in the church. After a Sunday service, each group holds a prayer meeting, followed by lunch, then a bible study session. They also attend a mid-week meeting. Once a year everyone goes away for a weekend retreat and there are regular group outings.

There are a vast number of church denominations to choose from and it is common to switch allegiance if one does not suit. In addition to Catholics, Methodists, Baptists and Episcopalians (the American equivalent of the Church of England), there are 80 different Presbyterian denominations. Most curious is the Jesus Holiness Church, which holds its services in a football stadium and features a soccer game between good and evil.

Students have begun to question whether Christianity, imported from the West, is suitable for contemporary Korea. As nationalism has increased, so a different, deep-rooted and ancient religion is being revived: Buddhism.

Buddhist temples, some from the 7th and 8th centuries, survive in the mountains. The religion cultivates detachment and monks search, through meditation, for a way to escape the cycle of birth, death and reincarnation. Buddhism also has an ecological dimension, which fits well with growing appeals to protect the environment.

In Seoul, the now well-established Christian Broadcasting Service has been joined by a new Buddhist Broadcasting System; Buddhist hymnbooks are now commonplace, setting old chants to Western hymn melodies, and many temples now run youth groups.