Holding up Friar Antonio de Sant'Anna Galvao as a model of rectitude and humility "in an age so full of hedonism," Benedict said the world needs clear souls and pure minds, adding: "It is necessary to oppose those elements of the media that ridicule the sanctity of marriage and virginity before marriage."
Benedict didn't elaborate, but his message for Brazilian Catholics reflected his uneasiness with the impact of popular culture on young people.
Earlier this year, Benedict declared that "any trend to produce programs and products - including animated films and video games - which in the name of entertainment exalt violence and portray anti-social behavior or the trivialization of human sexuality is a perversion."
Later, meeting with the country's 430 bishop's in Sao Paulo's cathedral, Benedict lamented that Brazil is in the midst of "difficult times for the church" amid "aggressive proselytizing" by born-again Protestant congregations.
The census says the percentage of Brazilians characterizing themselves as Catholics dropped from 89 percent in 1980 to 74 percent in 2000, while those calling themselves evangelical Protestants rose from 7 percent to 15 percent.
Benedict's message on immorality could be a tough sell in hedonistic Brazil. Sex before marriage is common. Scantily clad actresses are the norm on hugely popular TV soap operas, and most women on Brazil's famed beaches wear bikinis that leave so little to the imagination.
"Nothing could be more countercultural than his message in Brazil, the land of the thong," said David Gibson, author of "The Rule of Benedict: Pope Benedict XVI and His Battle with the Modern World."
Brazilian news media said the crowd reached about 1 million - as church officials had hoped for - although there were large empty spaces on the airfield in South America's largest city.
Benedict pronounced the sainthood of Galvao, a Franciscan monk credited by the church with 5,000 miracle cures, while he sat on a throne of Brazilian hardwood, surrounded by Latin American bishops and choirs of hundreds.
Galvao is the first native-born saint from Brazil, home to more than 120 million of the planet's 1.1 billion Catholics, and the 10th to be canonized by Benedict.
His canonization continues a push for saints in Latin America and elsewhere in the developing world that began under John Paul II, who sought role models as part of the church's worldwide reach. John Paul canonized more saints than all of his predecessors combined.
"Do you realize how big this is?" asked Herminia Fernandes, who joined the multitude at the airfield for the open-air Mass. "It's huge, this pope is visiting Brazil for the first time and at the same time he is giving us a saint. It's a blessing."
Galvao, who died in 1822, began a tradition among Brazilian Catholics of handing out tiny rice-paper pills, inscribed with a Latin prayer, to people seeking cures for everything from cancer to kidney stones.
Although doctors and even some Catholic clergy dismiss the pills as placebos or superstitious fakery, cloistered nuns still toil in the Sao Paulo monastery where Galvao is buried, preparing thousands of the pills for free daily distribution. Each one carries these words: "After birth, the Virgin remained intact. Mother of God, intercede on our behalf."
After canonizing Galvao, the pope hugged Sandra Grossi de Almeida, 37, and her son Enzo, 7. She is one of two Brazilian women certified by the Vatican as divinely inspired miracles justifying the sainthood. She had a uterine malformation that should have made it impossible for her to carry a child for more than four months, but after taking the pills, she gave birth to Enzo. "I have faith," Grossi recently told The Associated Press. "I believe in God, and the proof is right here." Benedict's trip has so far focused on reinforcing church doctrine on abortion, sexual morality and euthanasia. At a rally Thursday night, he instructed young Catholics to avoid premarital sex, remain faithful once they are married and to promote life from "its beginning to natural end." The latter was - at least in part - a reference to abortion, the issue that has dominated Benedict's first papal visit to Latin America. The pope also warned against drug use, violence, corruption and the temptations of wealth and power - themes sure to resonate across the region. Benedict, now 80, a pianist and lover of Mozart, showed his suspicions about popular culture in the 1990s when he acknowledged publicly he was opposed to a performance by Bob Dylan for John Paul II in Bologna, Italy. He said Dylan and other rock performers at the event were committed to a different message than John Paul's and he saw no reason for such so-called "prophets" to intervene. The pope heads Friday evening to the shrine city of Aparecida, about 100 miles from Sao Paulo, where he will visit a drug treatment center Saturday and open a conference of Latin American and Caribbean bishops on Sunday. Aparecida is the most important Catholic religious site in Brazil, home to the mammoth Basilica of Aparecida and the 3-foot statue of a black Virgin Mary called "Our Lady Who Appeared," the patron saint of Brazil. The statue was pulled from a river in the 18th century by poor fishermen who were not catching any fish, and then caught loads in their nets. Miracles were subsequently attributed to the statue, and so many pilgrims flocked to Aparecida that the church built the basilica and inaugurated it as a shrine in 1955. (AP) Associated Press writers Tales Azzoni and Alan Clendenning contributed to this report. AP-CS-05-11-07 1837EDT