A weak, emotional Pope John Paul was wheeled on Thursday into the same square where 25 years ago he first stepped out as pontiff, and said God wanted him to continue leading the Catholic Church despite his frailty.
Applauded by tens of thousands of pilgrims, the 83-year-old pope recalled the day in 1978 when he was elected by cardinals in the Sistine Chapel and said he had trembled under the weight of the responsibility entrusted in him.
His body now trembles from Parkinson's disease and is pained by arthritis, but the Polish pope made clear he intended to remain in charge of the billion-member Church until his death and will not resign as some have speculated.
"He (God), while knowing my human fragility, encourages me to respond with faith...and he invites me to assume the responsibilities that he himself has entrusted to me," the pope said in a homily during an open-air Mass.
Choirs sang and bells tolled as the sun set behind the imposing St Peter's Basilica during the service, which was celebrated at the same time that cardinals sent up white smoke on October 16, 1978, to announce the election of John Paul.
"Today, dear brothers and sisters, I am happy to share with you an experience which has been going on for a quarter of a century," the pope said, his speech slurred and slow. Few could have predicted in 1978 that the first non-Italian pope in 455 years would throw off the stiff trappings of the papacy and take his message far beyond the confines of the tiny Vatican state.
He became a major international player who crusaded for peace, worked tirelessly toward Christian reconciliation with the Jews and helped bring down communism.
But not everything he has done has won him praise: critics say he has divided his Church more than any predecessor with his hardline proclamations against contraception, abortion, married priests and women clergy.
PRAISING THE PAPACY
Clad in resplendent gold robes, the pope appeared watery-eyed as one of his top aides, Cardinal Joseph Ratzinger, praised his papacy, already the fourth-longest in the history of the 2,000-year-old Church.
"Holy Father, today the entire Church thanks you for the service you have given in 25 years. Even non-Catholic brothers and sisters, men of good will of other religions and convictions thank you," Ratzinger said.
As the Silver Jubilee has neared, the pope's health has appeared to go into steep decline. Speculation about how long he might live or who might succeed him have inevitably cast a long shadow over the festivities.
"I was here the day that they announced his election. He was filled with energy, filled with dynamism, and 25 years later it's gone," said U.S. Cardinal-designate Justin Rigali of Philadelphia.
Many cardinals have declined to talk about the pope's ailments and insist his papacy is still active. But other visitors to the Vatican on Thursday were clearly concerned.
"We felt we had to be here for his anniversary because it may be his last," said Filippo Belfiore, a retired fisherman from Sicily, who says he recovered from a coma after his family prayed to the pope.
Earlier in the day, the pope kicked off the celebrations by signing a 192-page document that he wrote on the role of bishops. It condemned religious fundamentalism and told rich countries not to lord it over the wretched of the earth.
"In many areas the world resembles a powder-keg ready to explode and shower immense suffering upon the human family," he wrote, adding that a "war of the powerful against the weak" seemed to be embroiling the world.
The celebrations continue on Friday with a concert and firework display. On Sunday, the pope will beatify Mother Teresa of Calcutta, India's revered "Saint of the Gutters."
The festivities reach their climax on October 21 when the pope elevates 31 prelates to the College of Cardinals -- the elite group that will choose his successor after he dies.