Ending a five-day trip to the most populous Catholic nation in the world, Benedict also warned that legalized contraception and abortion in Latin America threaten "the future of the peoples" and said the historic Catholic identity of the region is under assault.
Like his predecessor Pope John Paul II, Benedict criticized capitalism's negative effects as well as the Marxist influences that have motivated some grass-roots Catholic activists.
"The Marxist system, where it found its way into government, not only left a sad heritage of economic and ecological destruction, but also a painful destruction of the human spirit," he said in his opening address at a two-week bishops' conference in Brazil's holiest shrine city aimed at re-energizing the church's influence in Latin America.
He also warned of unfettered capitalism and globalization, blamed by many in Latin America for a deep divide between the rich and poor. The pope said it could give "rise to a worrying degradation of personal dignity through drugs, alcohol and deceptive illusions of happiness."
Benedict, speaking in Spanish and Portuguese to the bishops, also said Latin America needs more dedicated Catholics in leadership positions in politics, the media and at universities. He also said the church's leaders must halt a trend that has seen millions of Catholics turn into born- again Protestants or simply stop going to church.
While Brazil is home to more than 120 million of the world's 1.1 billion Catholics, the census shows that people calling themselves Catholics fell to 74 percent in 2000 from 89 percent in 1980. Those calling themselves evangelical Protestants rose to 15 percent from 7 percent.
"It is true that one can detect a certain weakening of Christian life in society overall," Benedict said, blaming secularism, hedonism and proselytizers for other sects.
In Aparecida and at events earlier this week in Sao Paulo that attracted more than 1 million people, Benedict roundly denounced immorality in a bid to counter the rising tide of Latin Americans flouting the church's prohibition on premarital sex and divorce.
Now, he said, the bishops must convince Catholics from all walks of life "to bring the light of the Gospel into public life, into culture, economics and politics."
Benedict did not name any countries in his criticism of capitalism and Marxism, but Latin America has become deeply divided in recent years amid a sharp political tilt to the left - with the election of leftist leaders in Bolivia, Ecuador and Nicaragua and the overwhelming re-election in Venezuela of President Hugo Chavez, an avowed socialist.
Other countries, such as Brazil, have center- left leaders who have come under heavy criticism for embracing free market economic policies that have widened the rift between rich and poor.
Benedict called the institution of the family "one of the most important treasures of Latin American countries," but said it is threatened by legislation and government policies opposed to marriage, contraception and abortion.
Mexico City lawmakers recently legalized abortion and gay civil unions, and the Brazilian government routinely hands out millions of free condoms to prevent AIDS.
Before addressing the bishops, Benedict said Mass before 150,000 faithful in front of the mammoth basilica of Aparecida, home to the nation's patron saint, a black Virgin Mary.
As hundreds of choir members sang hymns and people waved flags from all over South America, the pope called the region the "continent of hope" and said the bishops must be "courageous and effective missionaries" to ensure the strength of the church. But the turnout fell far short of the 400,000 to 500,000 worshippers local organizers hoped would show up for Benedict's last big public event of the papal tour, his longest since becoming pope two years ago. The 80-year-old pope also said the church needs to work harder to get its message across on the Internet, radio and television - methods used effectively by Protestant congregations attracting legions of followers, particularly in the vast slums ringing Brazil's largest cities. Waiting to catch a glimpse of the pope at Aparecida's basilica, 68-year-old Maria Costa said Brazilians needed to hear his message and she hoped his trip would revitalize the church. "Catholics weren't feeling very good with the Church, and that's why so many were leaving," she said. "I think that could change now. Let's hope so." (AP) Associated Press Writer Tales Azzoni and Alan Clendenning contributed to this report from Aparecida and Sao Paulo. AP-CS-05-13-07 2143EDT