Vatican City • Pope Francis urged Catholic bishops on Wednesday to dream of a future free of the mistakes and sins of the past as he opened a global gathering of the church leadership amid renewed outrage over the priestly sex abuse and cover-up scandal.

Francis celebrated Mass in St. Peter’s Square with some of the more than 200 priests, bishops and cardinals summoned to Rome for a monthlong meeting on proposing new ways to minister to today’s young Catholics.

Francis prayed for the bishops to guide the young with experience but also to rekindle in themselves the gift of “dreaming and hoping” that young people have.

He prayed for God’s help to ensure that the church “does not allow itself from one generation to the next to be extinguished or crushed by the prophets of doom and misfortune, by our own shortcomings, mistakes and sins.”

The Oct. 3-28 synod is opening under a fresh cloud of scandal with new revelations about decades of sexual misconduct and cover-up in the U.S., Chile, Germany and elsewhere. That has sent confidence in Francis’ leadership to all-time lows among the American faithful.

A survey by the Pew Research Center released on the eve of the synod found that 31 percent of U.S. Catholics felt the pope was doing an excellent or good job in addressing the abuse issue, down from 45 percent in January and 55 percent in 2015.

Some abuse survivors planned a sit-in near the Vatican as the synod opened, hoping to draw attention to their plight and compel delegates to prioritize the issue.

“Young people should question the way the church has dealt with this in the past,” said Matthias Katsch, a German member of the Ending Clergy Abuse global advocacy group. “We are looking for a new generation to accept that survivors have the right to have justice for what happened to them.”

Among those participating in the protest are the hearing impaired victims of the notorious Antonio Provolo Institute in Verona, Italy, where deaf children were sodomized for years by Catholic priests and brothers. The victims have found no justice even though Francis and the Vatican were informed of their plight in 2014.

Francis didn’t refer directly to the abuse scandal in his homily, but he did urge the synod members to “reverse situations of uncertainty, exclusion and violence, to which our young people are exposed.”

Let us “transform those frames of mind that today paralyze, separate and alienate us from young people, leaving them exposed to stormy seas, orphans without a faith community that should sustain them, orphans devoid of a sense of direction and meaning in life,” he said.

Francis visibly and audibly choked up during his homily when he welcomed two Chinese bishops to the gathering. Their presence, the first time Chinese bishops have attended a Vatican synod, was made possible, thanks to a landmark agreement with Beijing over bishop nominations that unified the Chinese Catholic leadership for the first time in decades.

“Today, for the first time, we have also with us two bishops from mainland China,” Francis said, pausing to compose himself. “We offer them our warm welcome.”

The presence of Bishops Guo Jincai of Gengde and Yang Xiaoting of Yan’an was of such significance that one of the pope’s communications advisers tweeted a selfie with them.