An estimated 150,000 factory workers, union leaders and liberal priests filled the Morumbi Stadium here to overflowing last night to hear John Paul II, the pope Brazilians have affectionately named "John of Gods," describe his vision of a "just sociey, in which the worker shares really and equally in the riches he is producing."

Before the pope arrived at Morumbi, the excitement was palpable. When he left an hour later, the crowd had erupted into spontaneous delirium, waving white handkerchiefs and placards as they shouted their approval.

Since his arrival in Brazil five days ago, John Paul has decisively reaffirmed the Roman Catholic Church's commitment to seek nonviolent social change, to fight repression on both the right and left, and to denounce political and economic injustice in Latin America, where perhaps as many as half the world's Catholics live -- most of them in poverty.

In language that papal observers describe as stronger than any he has used in the past, John Paul has made clear that "the civilization of love has no room for terror, torture, repression, inequality of income or other economic and social injustice."

Although this statement may not seem startling to Americans or Western Europeans, it is strong stuff in the context of Latin America.

"There persists [in Brazil and other Latin countries] a big gap between a minority of the rich on one hand, and the majority of those who live in want and misery on the other," John Paul said last night.

"The persistence of injustice . . . threatens the existence of society from within. This menace exists when the distribution of goods is used only in the economic laws of growth and bigger profit, when the results of progress reach only superficially the huge layers of the population," the pope said in reference to the laissez-faire economic models used by military governments in Brazil, Chile, Argentina and Uruguay.

The pope said it is "the duty of all, principally of those who hold economic and political power" to "acquire the spirit of the poor" and undertake reforms that ameliorate social inequities. Power, he said, "should never be used to protect the interests of one group to the disadvantage of others."

The pope specifically endorsed the right of workers to strike for decent salaries, to organize unions, to seek and obtain reasonable working conditions and to share in the economic development of their countries. These battles have already been fought in the United States and Europe but are still highly political issues in Brazil today.

At the same time, the pope cautioned that the church does not condone violence or "the clash between classes" in the fight to obtain social justice. "Nothing can be constructed with hatred or the destruction of others," the pope said last night.

During his travels in Brazil, John Paul has been very careful to champion the cause of social reform, supporting the position of Sao Paulo's archbishop, Cardinal Paulo Evaristo Arns, while cautioning Brazil's more radical priests to avoid Marxist alliances that could lead toward antagonism among classes and violent revolution.

In a major address Wednesday to the Episcopal Council of Latin America, the pope said it was the proper role of the church to "denounce injustice in order to defend man when his rights are wounded," but not to "provoke or deepen dissension to worse conflicts or to become involved in them."

On the contrary, he said, the church should try to "invite people and groups to dialogue . . . in certain circumstances, it will even come to be a mediator."

He endorsed the "theology of liberation" adopted by the Latin American church, although he cautioned that liberation of the poor and oppressed must be in line with Christian rather than Marxist concepts.

The pope also implicitly defended the Brazilian church's controversial support for strikes and other forms of peaceful economic and social change when in last night's speech, he told the workers that their right to organize and strike long had been recognized by the church.

In his address to the Episcopal Council, however, the pope made it clear that priests should not lead strikes, union movements or political parties. This responsibility belonged to laymen who "cannot excuse themselves from a serious commitment to promotion of justice and the common good," the pope said.

Latin America's radical priests view the pope's insistence on social change without violence or class antagonism as unrealistic. Many of them borrow the Marxist view that the ruling classes, supported by the military, govern to benefit their own interests and without concern for correcting social injustices.

But Leonardo Boff, a priest and leading liberal theologian here, said that he found the support for the liberation theology in John Paul's statements here.

John Paul, Boff said, has "supported, in the clearest words, the church's defense of human rights and [quest for] a humane society to be achieved without ruptures."