Pope John Paul II today called for an end to "flagrant injustices" here, citing torture, abductions and the violations of "man's right to life" as crimes and a "very grave offense against God."

In the name of his church, the pontiff asked the government of President Efrain Rios Montt for "effective" laws to protect Guatemala's long-oppressed Indian majority and demanded that his priests and nuns, many of whom work among the Indians, be allowed to "exercise their mission in safety and unhampered."

In two stern homilies, one delivered in the capital this morning and the other before hundreds of thousands of Indian peasants in the provincial city of Quetzaltenango this afternoon, the pope acted to renew the strength and confidence of a church that has had at least 10 of its priests murdered since the mid-1970s, while others were driven out of the country and a few joined the ranks of leftist guerrillas.

Greeted at the airport last night with one of Rios Montt's oft-repeated expressions of faith that God will rescue Guatemala from its troubles, the pope today asked a crowd of more than 300,000 on the capital's main military parade ground, "What use is it if someone says 'I have faith' but he has no works? Man is justified by his works and not by his faith alone."

"Faith teaches us that man is the image and likeness of God," John Paul continued as Vatican flags waved above the attentive crowd. "That means that he is bestowed with an immense dignity; and when man is downtrodden, when rights are violated, when flagrant injustices are committed, when he is submitted to tortures, done violence to by abductions, or one violates his right to life, one commits a crime and a very grave offense against God."

The crowd erupted into a long cheer.

The almost 6 million Catholics here have seen their churches used as Army barracks in some areas, their lay workers assassinated--a catechist in the province of Izabal was murdered by "unidentified men in uniform" only eight days ago--and their congregations depleted by fundamentalist Protestant sects that include among their followers President Rios Montt, a born-again Christian.

International human rights groups have estimated that several thousand civilians have been killed by the Guatemalan armed forces and rightist death squads during the administrations of Rios Montt and his predecessor, Gen. Romeo Lucas Garcia. The Guatemalan government maintains that most killings are the work of leftist guerrillas fighting to overthrow it.

Tensions between the Vatican and the government here intensified last week when six men convicted of subversive activities in closed-door trials were executed despite the pontiff's plea for clemency. The pope has made no public reference to the case since his arrival last night. But a Vatican communique Friday called the firing squad executions "incredible," and even senior members of the government now say privately that the executions were "not very well calculated."

In his visits last week to Costa Rica, Nicaragua and Panama, and yesterday in El Salvador, the Polish-born pope studiously distanced himself and his church from the Marxist ideology embraced by some priests as the only means to bring about the social revolution they see as desperately needed in the region.

But today, here, John Paul put new emphasis on his vision of the church as a force for major social change.

The Roman Catholic Church "has raised and continues raising its voice to condemn injustices, to denounce abuses, above all against the most poor and the humble," said the pontiff, "not in the name of ideologies, be they of whatever stripe, but in the name of Jesus Christ, of his gospel, of his message of love and peace, of justice, truth and liberty."

The Rios Montt government took power in a coup on March 23 of last year and has tried to change Guatemala's image as one of the hemisphere's most relentlessly, violently repressive societies.

On the basis of apparent improvements in human rights at the end of last year, the Reagan administration is in the process of renewing previously blocked military aid to the government here. But the pope appeared unconvinced.

Many of the priests who assisted him in a mass here today told of recent events in the countryside that give little cause for reassurance. In the village of Las Canas in Izabal, said one priest, a catechist named Felipe Caal, who was arrested and tortured once and threatened many times by soldiers last year, was shot by a group of uniformed men as he gave a Bible lesson a week ago Sunday.

Senior church officials reportedly have told the pope that persecution of Guatemala's Indians, while somewhat more subtle and scaled down in the past few months, is still fierce.

In his homily this afternoon in Quetzaltenango, where descendents of the ancient Maya civilization gathered by the hundreds of thousands in their brightly woven finery, John Paul told the Indians they are the objects of his "special interest" because "you are the most needy."

John Paul demanded that the Indians be allowed to practice their faith freely, and he warned, "No one must attempt to confuse ever again evangelization with subversion." Standing in front of a thatched structure like the primitive homes in which many Indians live, John Paul told these people, who make up most of Guatemala's population but have lived as serfs since the Spanish conquest, that "no one must scorn or mistreat another man."

The church must "raise its voice of condemnation when your dignity as human beings and children of God is violated. It wants to accompany you peacefully, as the gospel demands, but decisively and with energy in achieving recognition and the promotion of your dignity and your rights as persons."

"For that reason," John Paul continued, "in this place and in solemn form, in the name of the church I ask of those who govern legislation that effectively spares you the Indians from abuses and gives you the environment and adequate means for your normal development."

Much of John Paul's message clearly was aimed at countering the inroads of Protestant fundamentalist evangelicals, some of whom reportedly have told their followers that the pope is the "anti-Christ."

After making major gains in the past few years, the fundamentalists have apparently been put on the offensive by the papal visit. One American elder of Rios Montt's Church of the Word, was asked on local television about last week's firing squad executions. He said they were justified, then added that Catholics "made themselves famous many years ago for killing a lot of people with the Inquisition."