Some 60 Christian dissidents march, arms linked and voices joined in singing "We Shall Overcome," into a spirited encounter with an equal number of plainclothes police outside a Seoul courthouse.

It is a stylized performance in which both sides play well-understood roles, and it happened again last week with the ususal inconclusive results: no arrests, no casualities and no reaction from the expressionless by-standers on the sidewalk.

It raises the question of just how relevant the indomitable but few SOuth Korean opposition avtivities are to the country's 35 million people standing on the sidelines. Students and clergy go unflinchingly to prison for their beliefs without ruffling the daily life of this bustling capital. Protest prayer meetings meetings are attended by a handful of the faithful. The streets are crowded with shoppers, not demonstrators.

Few dobut that in or out of prison, President Oark Chung Hee's opponents will fight on. With a lifetime of resistance to Japanese, Soviets and now his fellow countrymen, respected Quaker leader Hahm Suk Hon said: "We must continue until all political prisoners are released." With other leaders, though, he wonders whether their struggle is receding in the national consciousness.

Although police-state controls on the press and speech prevent any accurate assessment of public attitudes, popular support of the self-sacrificing opposition does appear to be eroding.

Independent political analysts and the trouble the potically volitile South Koreans are keeping unusually silent for three reasons.

Since the fall of Vietnam in 1975, President Park has played on fears of invasion from Communist North Korea, depicting anti-government resistance as encouragement to North Korean President Kim Il SUng and hence dangerous to national security. The fiercely anti-Communist South Koreans are unable to judge whether the war risks are deliberately exaggerated, as many informed foreigners believe.

Park's personal management of the booming economy has brought him wide support. The crash industrialization program and the transformation of Seoul into a high-rise city have aroused national pride and general raised living standards. Ordinary people still have resentments and the aloof president is more respected than liked, but so long as jobs and incomes are expanding discontent is expected to stay will below the levels that led riots in the past.

A sophisticated secret-police apparatus and dacronian laws frighten anyone not ready to go to prison for such innocuous acts as distributing leaflets favoring democracy.

After years in the government's grip, the three traditional centers of opposition - the students, non-government political parties and Christian activists - ar efragmented, demonralized and virtually powerless.

The country's 225,000 college students are under tight surveillance because of their historic role as king breakers. Student riots brought down the Sygman Rhee dictorship in 1960 and unwittingly paved the way for then-Gen. Park's coup a year later. Prestigious Seoul National University, once a hotbed of activism in the center of the city, has been relocated on the autskirts, with a large police headquarters nearby.

Compulsory military training, the infiltration of the campuses by the Korean Central Intelligence Agency and pressure on faulty members to report activists are all designed to forestall major demonstrations. Theresultant distrust makes true feelings hard to plumb.

Conventional political opposition appears spent. Barred by Psrk's consitutional changes, from helping to shape policy, they sit in an emasculated public esteem. Government control of the news media has deprived the politicians of any forum for a serious review of Park's government, and the experience of the few who dared to try has not been encouraging.

The most crippling restriction is a two-year-old emergency decree prohibiting criticism of President Park or the 1972 constitution, which gave him virtually limitless powers. The major opposition party, the New Democratic Party, is in the latest of a series of leadership struggles. The issue is always the same - how to find a tenable role for opposition politics under a dictatorship intolerant of any dissent. The party holds 55 of the 219 seats in the National Assembly.

As government restrictions gradually silenced press and political dissent, the burden of resistance to the deprivation of human rights has fallen on a dedicated minority among South Korea's 5 million Christians.

The 4 million Protestants and 1 million Catholics are seriously divided between conservative progressive wings. The National Council of Churches in Korea, housed in the 11-story Christian Building in Seoul, claims 2.5 million Protestants in its member churches. It is the heart of humnan-rights protest. Other Protestant groups, enthusiastically supported by the government, defend restraints on liberty as necessary in a time of national emergency.

Firmly implanted by late-nineteenth-century missionaries, Christianity is a major factor in Korea life. Although only 14 per cent of the population, Christians have exerted a disproportionate influence in education and national leadership.

Frequently the government's attempts to halt dissent provoke further protests and more arrests. The church concern over human rights has led to a loose alliance with Western-educated politicians dedicated to the same ideas.

"Our leaders believe we must work to fulfill the just society," said a Protestant activist. "Where we see injustice we must speak out."

Among foreign observers there is a consensus that the dissidents are losing ground in the contest to win over the great majority that is either strongly pro- or anti-Park. "Our main project now is to get the people's participation in the drive for democracy," said a young intellectual.

The government depicts the opposition as a handful of dangerous troublemakers who enjoy no popular following. Yet the measures it takes to silence these critics appear to contradict that view. Park appears unchallengeable while the economy keeps growing, but dissident spokesman insist that he has substantial hidden opposition.

Additionally, the dissidents see several long-term factors in their favor: The present form of government is designed to function under one man and may not survive the eventual succession; the national security argument will wear thin as South Korea's economy and war-making potential outdistance North Korea's; the emerging middle class and the Western-educated leaders of the next generation will eventually force liberalization in the press and speech.

Barring any major setback to the government such as a world recession, Park is likely to maintain his present clear edge over the dissidents. Again that, democracy and the desire for freedom have taken a tenacious hold in South korea.