For four days during Easter festivities, a dusty hillside in South Africa's northern Transvaal Province swarmed with more than a million African pilgrims who came for their annual spiritual recharge in the presence of their own black bishop.

This was the Easter "conference" of the Zion Christian Church, biggest of the religious denominations that are springing up almost daily in South Africa's black community and that collectively form by far the country's largest organized African movement.

The nation's blacks--legally restricted in their political activity--are viewed widely as turning to religion as an emotional outlet and a way of sustaining their utopian dreams. Some denominations practice a spiritual, if not political, militancy. The Nazarite Church in Natal Province worships a black Messiah who guards the gateway to heaven and bars whites from entering. "Nobody can rule twice," the whites are told.

The Zion Christian Church conference was a huge, emotive affair. Half was modern Christian revivalism--divine healing, immersion in water and speaking in tongues--and half was traditional African ancestor worship and smelling out of evil spirits.

The scene was a farm in the arid countryside 200 miles north of Johannesburg. It was bought by the denomination's founder, Engenas Lekganyane, in 1912 and named after Zion City, Ill., the headquarters of an apocalyptic healing movement founded by John A. Dowie in 1896.

The pilgrims came in 5,000 chartered buses from all parts of South Africa and neighboring black states to this holy place. Engenas' grandson, 27-year-old Bishop Barnabas Lekganyane, presided over the ceremonies, which were translated into six languages.

The Zion Christian Church is a movement of exploding growth that exerts a profound influence over its followers. Yet such is the insularity of South Africa's segregated society that whites know hardly anything about it, except that it causes a traffic problem on the northern road every Easter.

Whites see people in flowing white robes walking about the streets on Sundays. They know that the Africans who wear a little silver star in their lapels do not drink and are good workers. That is about the extent of their knowledge.

The denominations began appearing all over Africa toward the end of the last century as a reaction against what is now being called the ecclesiastical colonialism of Western Christian missionaries.

In South Africa they began multiplying at an astonishing rate when Afrikaner nationalism came to power in 1948 with its policy of intensifying the denial of political rights to blacks and applying the system of legally enforced segregation called apartheid.

There were 800 denominations in 1948. Today there are 3,700, which claim 30 percent of the total African population of 20 million as followers.

The denominations obviously have the potential to go over to political action, but so far there is no sign of this. They appear instead to be a substitute for politics, which has become too dangerous and unproductive for blacks under the white man's proscriptive laws.

"Generally speaking, the sects are quietistic," says Gerhardus C. Oosthuizen, professor of religion at the University of Durban-Westville, who has been studying them for 20 years.

"We have no time for politics," says the Zion Christian Church's liaison officer, Lesetja Mabe. "We have too much other work to do."

Indeed the Zion Christian Church seems almost obsequious. Shouting guards cleared a path through the milling crowd for the white reporter's car when he arrived at the Easter conference at Moria.

The walls of the reception room for visitors are hung with portraits of the country's white political leaders and dead Afrikaner heroes.

Bishop Edward Lekganyane, Barnabas' father, in 1965 thanked the minister for African affairs for leading the blacks to "orderly freedom," adding: "In our church there is no room for people who undermine national security and break the law."

On the other hand, the denominations represent a revolt against white domination and constitute a massive independence movement in the ecclesiastical domain.

The South African Students Organization, forefather of the country's militant black consciousness movement, recognized the Zion Christian Church's role in resistance by electing Bishop Edward its honorary president in 1973.

One sign of the denominations' rebelliousness is the Nazarites' reversal of the color bar in heaven. Their founder Isaiah Shembe, now dead but worshiped as having been resurrected, preached that whites have already received their good things during their lifetime on earth.

Other denominations have also downgraded the pale white Christ and almost replaced Him with a black Messiah.

In the proliferation of denominations, many are started for no better reason than to give their founders a taste of leadership and a fancy title. Some are run by charlatans.

Some strike a note that a Western observer finds amusing. The expurgating of evil spirits is of fundamental importance in traditional African society: sometimes they must be flushed out of the body; sometimes they must be washed off. Some churches have thus adopted names reflecting the importance of these rituals, such as the Castor Oil Dead Church and the Sunlight Soap Church.

Broadly, the denominations can be divided into the Ethiopian churches and the Zionist ones.

The Ethiopian churches, founded in the 1890s, took their name from the only country in Africa that was independent at the time. The Zionist denominations have nothing in common with modern Jewish Zionism and have their roots in Dowie's movement in Chicago, the Christian Catholic Apostolic Church in Zion. The Zionist movement has many white Afrikaner adherents, who belong to a church called the Apostolic Faith Mission.

The black Zionist denominations split constantly over leadership conflicts and doctrinal differences. All have one thing in common: an enveloping warmth at their gatherings and a collective psychology of mutual support and protection.

"I shall be safe when I go home," said one old man at Moria on Easter, clutching two packets of "Zion tea" that had been blessed by Bishop Barnabas. He can always recognize his fellow congregants by their silver stars and greet them in the names of Engenas, Edward and Barnabas.

Members of the church appear to take vicarious pleasure in the wealth of its leaders and bestow expensive gifts on the bishops.

Barnabas' father, Edward, used to sport a huge diamond ring and at one stage had 45 automobiles, including specially imported Cadillacs.

Barnabas, more modest, has sold some of the cars. "But he still has plenty," said a follower, "and that makes me feel good."