Sydney - Even jaded business travelers were smiling Friday as gleeful pilgrims rejoiced in Sydney airport at the prospect of a week of spirited worship organized by the Catholic Church and presided over by Pope Benedict XVI.

The pope doesn't arrive in Australia's biggest city until Sunday and the World Youth Day (WYD) celebrations don't kick off until Monday but it was joy unbounded as the first of 125,000 young Christians swept through the arrivals terminal on their way to a date with the 81-year-old pontiff.

WYD, begun in Rome in 1986 and held somewhere in the world every three years, is sometimes called the Catholic Olympics because of its uplifting spirit and power to bring hundreds of thousands of people together in the one place.

Organizers have registered 225,000 pilgrims from 170 countries and expect up to 500,000 to be there for the pope's closing Sunday Mass on July 20.

Rugged up against a harsh winter wind blowing off the harbour, Richard Tan and his chums from Singapore are mixing with thousands of like-minded visitors thronging the city centre.

Unlike Sydney's 2000 Olympics, where events were dispersed and held over three weeks, the WYD celebrations are focused around the harbour and collapsed into a frantic few days that Tan expects will bring lots of inspiration but little sleep.

"It's just good to be with other young people," he beamed. "We all hope to see the pope."

The Holy Father arrives by boat on the harbour on Thursday in what all expect to be the signature image of the week-long jamboree.

Pilgrims are billeted in private homes, in schools, even 13,000 of them at the gigantic Olympic Stadium an hour's train ride from the harbour.

In a fillip for religious tolerance, 281 of them will bed down in classrooms under the stewardship of the Islamic students of Malek Fahd School. Pupil Rose-Ann Awed told national broadcaster ABC that "it's part of our faith to make them feel welcome, no matter if they're Catholic or Jewish, because it's part of our faith, it's our duty."

A quarter of Australia's 21 million people say they are Catholic but less than 15 per cent attend church regularly. The mission of WYD is to help rekindle faith in a country that rated in a recent survey as one of the world's least godly.

There are those committed to making the pilgrims feel unwelcome. Rachel Evans, 33, leads the NoToPope Coalition, which is pledged to gather gays, lesbians, anarchists and civil libertarians for marches next week under banners proclaiming "Defend the Right to Protest, No to Homophobia, No to Anti-Condom Policies."

The coalition intends handing out condoms to young Catholics in town for the papal party. Ready to take on the condom-vendors are their ideological counterparts in the Australian Council of Natural Family Planning.

"We're ready for them!" the council said in a statement. "Despite popular belief, the church isn't against sexuality. On the contrary, the church wants everyone to develop a deeper, richer understanding of the meaning of sex and sexuality." (dpa)