SYDNEY, Australia — Pope Benedict XVI ended his farthest pilgrimage Sunday, one intended to inspire a new generation of faithful while trying to overcome a dark chapter for his church from a clerical sex abuse scandal.

Summing up his message, Benedict told young pilgrims at a Mass in Sydney that a "spiritual desert" was spreading throughout the world and challenged them to shed the greed and cynicism of their time to create a new age of hope.

The Vatican said some 350,000 faithful from almost 170 countries packed the Randwick race track — many of them camping out in sleeping bags in the mild chill of the Australian winter — as well as a global television audience.

Vatican spokesman the Rev. Federico Lombardi said it was Sydney's biggest crowd since the Olympic Games in 2000.

Asked how the 81-year-old pope fared with the audience at the World Youth Day event — alternately football-stadium boisterous or chapel quiet depending on the occasion — Lombardi said Benedict's speeches were "positive, constructive, never polemical."

Benedict touched on themes for the universal church as well as Australia in particular — raising the need for the world to change its lifestyles because of global warming, relations with non-Catholics and the struggle here to rejuvenate a crisis-battered Church.

At Sunday's Mass under threatening skies, Benedict urged young Christians to be agents of change because "the world needs renewal."

"In so many of our societies, side by side with material prosperity, a spiritual desert is spreading: an interior emptiness, an unnamed fear, a quiet sense of despair," the pontiff said.

The pope said it was up to a new generation of Christians to build a world in "which God's gift of life is welcomed, respected and cherished — not rejected, feared as a threat and destroyed."

They must embrace the power of God "to let it break through the curse of our indifference, our spiritual weariness, our blind conformity to the spirit of this age," he said.

The aim was "a new age in which hope liberates us from the shallowness, apathy and self-absorption which deadens our souls and poisons our relationships," he said.

It is a primary theme of his papacy, with him acknowledging on his way to Australia that the Church in the West was "in crisis" because people no longer see the need for God. But he insisted it was not in decline. "I am an optimist" about its future, he said.

Benedict announced that, as expected, Madrid, Spain, would host the next World Youth Day in 2011 and told the pilgrims.

The more than 20 hour flight from Rome to Australia was the longest distance Benedict has traveled as pope.

He flew over the scene of the Mass early Sunday in a helicopter — dubbed "the holy-copter" by bleary-eyed pilgrims below. He saw the assemblage swarming all over the track in a jumble of sleeping bags and backpacks.

"It's been crazy, hectic, nuts — but it's also been serene, calming and very fulfilling," said Margaret Mazzella, 48, of Westchester, New York, as she rested on a sleeping bag and picked at a tuna sandwich following the festival's final Mass on Sunday.

He later drove slowly through the crowd, stopping once to kiss the forehead of a toddler held up to the popemobile's window. Pilgrims gave him a rock-star welcome, waving the flags of their nations, cheering and chanting his name.

Some pilgrims at World Youth Day complained Pope Benedict XVI sped past them during two drive-throughs in Sydney — so quickly they barely caught a glimpse of the pontiff before he was gone.

Australian media gave prominent attention to Benedict's apology Saturday for the sexual abuse of minors by Catholic clergy, headlining his word's "I Am Deeply Sorry."

He said he wanted "to acknowledge the shame which we have all felt" and called for those responsible to be "brought to justice." The acts were "evil" and a "grave betrayal of trust," he said.

The pope's apology was not enough to satisfy representatives of the victims of clergy sexual abuse, who said it must be backed by Vatican orders to Australian bishops to stop what they say are efforts to cover up the extent of the problem and to block survivors' attempts to win compensation.

The apology followed similar statements in the United States in April, where he also met with a small group of victims.

Even as the papal entourage prepared to leave Monday morning, it was still unclear whether Benedict would do the same in Australia. Lombardi would not rule out the possibility in the waning hours of the visit.

The pope was due to leave Australia for the Vatican on Monday.

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Associated Press Writer Rohan Sullivan in Sydney contributed to this report.