Pope Francis on Thursday emphasized church advancement in his first Mass with the cardinals who elected him pontiff a day earlier.

With solemnity, he delivered a homily about moving the Catholic Church forward to the cardinal electors, who were dressed in light yellow robes. Altar servers burned incense in the Sistine Chapel, the setting for the Mass.

Speaking in Italian, Francis didn't use a script and kept the sermon short, calling on the cardinals to have courage.

"When we don't walk, we are stuck. When we don't build on the rock, what happens? It's what happens to children when they build a sand castle and it all then falls down," the new pontiff said.

"When we walk without the cross, when we build without the cross and when we confess without the cross, we are not disciples of Christ. We are mundane," he said. "We are all but disciples of our Lord.

"I would like for all of us, after these days of grace, that we find courage to walk in the presence of God ... and to build the church with the blood of Christ," the pope continued. "Only this way will the church move forward."

During the service, the cardinals prayed for the new pope and Pope Emeritus Benedict XVI so "that he may serve the Church while hidden to the world, in a life dedicated to prayer and meditation," the Vatican said.

When Jorge Bergoglio stepped onto the balcony at the Vatican on Wednesday evening to reveal himself as the new leader of the world's 1.2 billion Catholics, he made history as the first non-European pope of the modern era, the first from Latin America, the first Jesuit and the first to assume the name Francis.

Francis began Thursday by praying at the Basilica of Santa Maria Maggiore in Rome, a place of special significance for the Jesuits.

His next public appearance is likely to be Sunday. The new pontiff will "very probably" celebrate Mass at St. Peter's and then deliver the traditional Angelus blessing, said the Rev. Federico Lombardi, a Vatican spokesman.

But it won't be until Tuesday that Francis will be formally installed as pope.

That's by design. The day coincides with the Feast of St. Joseph, the patron saint of Italy.

In a letter dated Wednesday to Rome's chief rabbi, the new pope promised "renovated cooperation" between Catholics and Jews.

"I vividly hope I'll contribute to the progress" of relations between Jewish and Catholic people that they "have known starting from the Vatican II Council" in the 1960s, Francis wrote to Riccardo Di Segni.

The new pope said he was also acting in a spirit of "helping the world to be always more in harmony with the will of the Creator."

The new pontiff will meet with all the cardinals, not just those who were eligible to vote for him, on Friday and will hold an audience with the media on Saturday, Lombardi said.

Already, a picture is emerging of a humble man who shies away from the trappings of his new status and is devoted to his pastoral duties.

As pope, Francis will have plenty to deal with. He takes the helm of a Roman Catholic Church that has been rocked in recent years by sex abuse by priests, and claims of corruption and infighting among the church hierarchy.

Reflecting the urgency of those concerns, a group representing the alleged victims of sexual abuse by priests has written an open letter to Francis requesting a meeting.

"Your predecessor met only a few times with a few carefully chosen victims in tightly choreographed settings, as he visited nations where this crisis had reached a fever pitch," the letter from the Survivors Network of those Abused by Priests states.