On a cool and cloudy Saturday morning in late April, evidence of the movement's vitality was plain to see. Representatives of 50 base communities gathered at the St. Paul the Apostle Church on the east side of this sprawling city, an area of humble workers' residences and squatter slums.

With four priests present, readings from the Bible alternated with more worldly concerns: criticisms of government proposals to reduce pensions and workers' rights under the Brazilian labor code. The service ended with the Lord's Prayer and then a hymn.

"In the land of mankind, conceived of as a pyramid, there are few at the top, and many at the bottom," the congregation sang. "In the land of mankind, those at the top crush those at the bottom. Oh, people of the poor, people subjected to domination, what are you doing just standing there? The world of mankind has to be changed, so arise people, don't stand still."

Afterward, discussion turned to other social problems, chief among them a lack of proper sanitation. A representative of the left-wing Workers' Party discussed strategies to press the government to complete a sewer project. Congregants agreed to organize a campaign to lobby for it.

In other areas here, liberation theology advocates have strong links to labor unions. At a May 1 Mass to commemorate International Labor Day, they draped a wooden cross with black banners labeled "imperialism" and "privatization" and applauded when the homily criticized the government's "neoliberal" economic policies, the kind Washington supports.

"We believe in merging the questions of faith and social action," said Valmir Resende dos Santos, a liberation disciple who brings base communities and labor groups together in the industrial suburbs here. "We advise groups and social movements, mobilize the unemployed, and work with unions and parties, always from a perspective based on the Gospel."

Since liberation theology first emerged in the 1960s, it has consistently mixed politics and religion. Adherents have often been active in labor unions and left-wing political parties and criticized governments they complain are beholden to modern-day Pharisees.

Supporters see that activism as a necessary virtue to answer the needs of the poor. Opponents say it dangerously insinuates the church into the temporal, political realm, and in recent years they have repeatedly announced the movement's decline or disappearance.

Some of the distinctions in this debate are finely drawn. John Paul II's reach extended into human rights and politics, as he discouraged abortion and divorce and encouraged fellow Poles and other Europeans to reject communism. He is widely credited with helping to bring about the eventual collapse of the Soviet Union.