The diminutive black bishop stabbed a finger toward the five stony-faced white commissioners sitting before him and declared: "We are on trial here for being Christians and that by a government which itself claims to be Christian . . . ."

Throwing his arms wide as though he were about to bless them, the bishop sought to explain what Christianity means to a black cleric living under the strict system of racial segregation in white-ruled South Africa.

"You whites brought us the Bible," he said, "now we blacks are taking it seriously. We are involved with God to set us free from all that enslaves us and makes us less than what he intended us to be."

Anglican Bishop Demond M. Tutu, who is general secretary of the South African Council of Churches, was the leadoff witness this week before a judicial commission appointed by the government to inquire into the council's activities and finances and make whatever recommendations it thinks fit.

The commission was appointed last year, amid rising government attacks on the church council, which is an ecumenical body representing all Christian churches in South Africa except the all-white Dutch Reformed churches, to which most government supporters belong.

The church council strongly opposes apartheid, while the Dutch Reformed churches have just been suspended by the World Alliance of Reformed Churches for practicing and condoning it.

South Africa's apartheid policy has been a constant concern of mainline churches in Western Europe and the United States. For more than a decade, church groups have led shareholder campaigns to try to force U.S. corporations out of South African business ventures because of apartheid practices. Nearly 20 years ago the World Council of Churches established an antiracism campaign that gave modest grants to groups combating racism throughout southern Africa.

South African Church Council funds, 90 percent of which come from churches in the United States and Europe, have been used to defend political prisoners, to sustain their families, educate their children and to assist refugees who have fled to neighboring states.

The commission will be investigating the council's interpretation of its Christian mission to see whether it is subversive, as well as studying its foreign connections and its financial records, which are in an admitted state of disarray.

The financial records are defective partly because of poor management and partly because the council deliberately did not record the names of some of the people it helped, especially during the 1976 Soweto riots when many fled the country, church officials say.

Some $10 million is said not to have been properly accounted for. These funds were disbursed before Tutu became general secretary, and the state has charged his predecessor, John Rees, with fraud.

The government regards Tutu, with his blunt attacks on apartheid and his growing status abroad, as a political threat and would like to see him discredited. The commission's hearings may provide an opportunity for that.

An adverse report from the commission could also lead to the invoking of a law to prevent the council's receiving money from abroad.

There are no specific charges to answer at the hearings. Tutu was the first witness as the open hearings began and his statement was an attempt to defend himself in advance of whatever accusations may be made by others.

All he had to go by were the government's generalized attacks, and the reports of two other judicial commissions appointed to inquire into entirely different matters but which criticized the church council.

One, a commission that inquired into the media, digressed for 242 pages to try to define Tutu's role in what it described as a "total onslaught" against South Africa by forces ranging from the World Council of Churches to the Soviet government and "the anti-South African establishment in the U.S.A."

One passage in the report stated: "There can be little doubt that the World Council of Churches and its close affiliate in South Africa, the South African Council of Churches, are actively engaged in violently anti-South African, left-radical liberation politics which include open support for the terror attack on South Africa--an attack they seek to sanctify by the invocation of the theology of revolutionary liberation."

The deputy chairman of that commission toured the United States last month, visiting conservative church groups to gather views about the South African council ahead of the hearings.

In his testimony, Tutu denied that the council is politically motivated. It operates from a divine constraint to live out God's word, he said, and this inevitably causes it to be concerned about social injustices.

"Our God does not permit us to live in a spiritual ghetto cut off from the real life out there." he said. "When God encounters injustice oppression, exploitation, he takes sides . . . Our God is not a God who sanctifies the status quo. He is a God of surprises, uprooting the powerful and unjust to establish His kingdom."

Tutu repeated earlier charges that apartheid is unchristian and unbiblical, noting that it has been declared a heresy by the World Alliance of Reformed Churches.

Man was created in the image of God, he said; to diminish man's dignity by racial discrimination was therefore blasphemous.

Tutu ended with a declaration of determination to continue his work whatever action the government might take against him or the council.

"I want the government to know now and always that I do not fear them," he said. "They are trying to defend the utterly indefensible. Apartheid is as evil and as vicious as nazism and communism and the government will fail completely for it is ranging itself on the side of evil, injustice and oppression."