Pope Offers Vision of Church for Millennium : Religion: He calls on youth to serve the poor and ill. Pontiff’s Central Park sermon is most orthodox of trip.

Speaking against the soaring New York skyline, Pope John Paul II celebrated an exuberant open-air Mass in Central Park on Saturday and held out his vision for the world’s 1 billion Roman Catholics as the church approaches its third millennium.

In a message aimed at the thousands of youthful faces in the crowd, the pontiff said: “You young people will live most of your lives in the next millennium. . . . You must transmit your joy in being adopted sons and daughters of God through the creative power of the Holy Spirit.

“Do not be afraid. The power of the Holy Spirit is with you.”

As he has throughout his visit to the United States, which ends today with a Mass in Baltimore, the Pope called on young church members to serve the poor, the hungry, the homeless, the lonely and the ill, including people with AIDS.

“You are called to stand up for life,” he proclaimed to applause from the 200,000 who gathered under gray skies in Central Park’s Sheep Meadow. Defending life, the Pope made clear, means opposing abortion, pornography, euthanasia and assisted suicide.

“Stand up for marriage and family life. Stand up for purity,” he urged.

Later, speaking under the vaulted arches of St. Patrick’s Cathedral, the Pope acknowledged that these are difficult times for parents who want to pass on their faith to their children.

“Sometimes you yourselves are not sure what the church stands for,” he said. “There are false teachers and dissenting voices. Bad examples cause great harm. Furthermore, a self-indulgent culture undermines many of the values which are at the basis of sound family life”--an apparent reference to the church’s controversial opposition to artificial birth control and female priests.

The answer to these moral questions, he said, is to be found in prayer and in the church’s catechism, which spells out its doctrines and moral teachings.

The Pope’s sermon in the park, with its frequent references to the Holy Spirit and the Virgin Mary, was his most religiously orthodox statement so far during the trip.

In previous addresses, John Paul appealed to his listeners’ social and moral values as he coaxed them to redouble their efforts on behalf of the downtrodden. This time his words were anchored firmly in Scripture and the 2,000-year-old tradition of the Roman Catholic Church.

His left hand trembling, the Pope spoke movingly of his youth even as he looked to the next century.

“I remember a song I used to sing in Poland as a young man, a song which I still sing as Pope,” he said. In a moment filled with poignancy, he sang it in Polish to the delight of the enthralled crowd.

“You applaud,” he said, a twinkle in his eye. “But did you understand?”

He said it was a tale of the shepherds called to Bethlehem at the first Christmas to see the newborn Jesus--the same story told in the familiar Christmas carol “Silent Night.”

“If I speak of Christmas, it is because in less than five years we shall reach the end of the second millennium, 2,000 years since the birth of Christ on that first Christmas night in Bethlehem,” he said. “We must allow the Holy Spirit to prepare us for this important event, which is another significant stage of His passage through history and of our pilgrimage of faith.”

Looking up from his text and gazing into the crowd, John Paul said that he loved them and that he knew they would do this. “Then you can tell the whole world that you gave the Pope his Christmas present in October, in New York, in Central Park,” he said, ending his homily.

Spontaneously, the crowd began singing “Silent Night” as the Pope, surprised and moved, looked on.

It was perhaps the most moving moment on a journey filled with moving moments.

At age 75, John Paul sees the millenium both as a symbol and as a reference point for his accomplishments and his goals.

These include converting more people to Catholicism and healing divisions within Christianity. He is particularly keen on a new unity with the Eastern Orthodox churches.

In a change of plans, the pontiff traveled to Central Park not in his heavily armored limousine but in the “Popemobile,” its clear top allowing his New York neighbors their first chance to see him. He is staying at the Vatican’s mission to the United Nations on Manhattan’s Upper East Side.

Before the service, John Paul walked onstage and delivered a weather report into the microphone. “Good morning,” he told the crowd in front of the altar. “Today, no sun.” The Pope then walked across the stage to greet members of the orchestra and chorus.

Mayor Rudolph W. Giuliani, who attended the Mass, said he was very proud of the way the pontiff was welcomed by all New Yorkers.

“We live in the world’s most diverse and international city,” Giuliani said, separating himself from fellow members of the Republican Party who favor restrictions on immigration. “New Yorkers know our city and our nation will continue to grow stronger as long as we open our hearts and minds to people all over the world. We are a city and a world of immigrants.”

The Pope’s massive audience included 120,000 ticket-holders who, if they arrived by 7 a.m., two hours before the service began, were allowed into an area that gave them an unobscured, if sometimes distant, view of the altar. Many of the tickets had been distributed in parish lotteries.

Thousands more had to be content with watching on giant television screens throughout the park.

All, however, faced a magnificent vista as the Mass began. Behind the purple-and-gold altar rose the vast expanse of the New York skyline, framed by gray-white clouds. At first, only a few of the midtown skyscrapers were tipped with fog, although later, as a light rain began to fall, the skyline disappeared into thicker clouds.

Bundled against the chill in a well-worn Brooklyn Dodgers jacket, Anthony Maranzano, a computer firm supervisor from Poughkeepsie, N.Y., said he had climbed aboard a parish-chartered bus at 3:30 a.m. with his 10-year-old daughter, Theresa, for the three-hour journey to Manhattan.

Asked why he had come, Maranzano said: “This was our only opportunity to see the Pope. I’d like to see him in Rome, but there was no immediate chance of that.”

Gesturing at the gray clouds, he added: “This is the best church to experience the Pope in. Look at the roof of this cathedral.”

The drizzle dampened the crowd but not its enthusiasm.

The audience, many wearing slickers and carrying umbrellas, was positioned behind yellow ropes on soggy ground covered with hay to absorb the moisture. Some families sat on quilts, blankets or plastic ground covers. Fathers held bundled-up tots on their shoulders to give them a view of the pontiff. Some of the tiny children waved small gold-and-white souvenir papal flags.

Many Latinos in the crowd cheered lustily when the Pope read portions of his homily in Spanish. Polish flags waved when he used Polish to sing the Christmas song.

While giving Communion, the priests were protected by Boy Scouts holding yellow and white umbrellas stamped with a seal of the Pope.

Some in the crowd paid careful attention to the Pope’s words.

“The message of ‘don’t be afraid of anything’ is very important,” said Carol Zarycki, a financial adviser. “It gives us all hope to know we don’t have to be afraid. He is giving a message to the world.”

For others, the content of the Pope’s message was less important than the fact that they were in the presence of their church’s spiritual leader. “I just wanted to stay near him,” said Susana Beltran, who traveled from nearby Passaic, N.J., to attend the Mass.

At the end of the Mass, when the pontiff waved to the crowds, almost all, including those in the farthest reaches of the lawn, waved back. They seemed to be waving more at the giant televisions than at the altar, for there was not much chance that the Pope could see them.

Times staff writers Stanley Meisler and Robert L. Jackson and special correspondent Helaine Olen contributed to this story.