Pope Francis used his annual Christmas address to demand that priests who have raped and molested children turn themselves in and to promise that the church would “never again” cover up clergy sex abuse.

“Let it be clear that before these abominations, the church will spare no effort to do all that is necessary to bring to justice whosoever has committed such crimes," Francis said to an assembled crowd of cardinals and bishops of the Roman Curia at the Vatican. “Convert and hand yourself over to human justice, and prepare for divine justice.”

The remarks are among the strongest Francis has delivered on the clergy sex-abuse crisis, which he said church officials have failed to treat seriously because of their “irresponsibility, disbelief, lack of training, inexperience, or spiritual and human shortsightedness.”

He vowed that a planned 2019 summit at the Vatican for all Catholic bishops would include detailed steps on preventing abuse, including in seminaries.

“This coming February, the church will restate her firm resolve to pursue unstintingly a path of purification," Francis said, according to a translated transcript. "She will question, with the help of experts, how best to protect children, to avoid these tragedies, to bring healing and restoration to the victims, and to improve the training imparted in seminaries.”

This summer, revelations about U.S. Cardinal Theodore McCarrick’s alleged sexual misconduct with seminarians and younger priests propelled the issue of seminary abuse into an ongoing national conversation about U.S. clergy abuse.

Francis also encouraged victims to come forward, and thanked the media for “unmasking” predators and making “their victims' voices heard.”

The address follows a year in which Francis has been criticized for his handling of a sex-abuse scandal in Chile and the allegations against McCarrick and other bishops accused of abuse or cover-ups. In October, Francis halted an attempt by the U.S. Conference of Catholic Bishops to vote on a series of reform proposals in order to address the issue in February at the full gathering of bishops worldwide.

In Pennsylvania, a second grand jury report revealing allegations of abuse of more than 1,000 victims over seven decades ignited a series of investigations by prosecutors around the country.

Zach Hiner, the executive director of SNAP, a clergy abuse survivors' group, said the pope’s words this week will be meaningless unless acted upon.

The last thing that Pope Francis should be doing right now is giving speeches about clergy sex abuse,” Hiner said in a statement. “Such a speech should come only after the pope has exhausted every avenue to remove abuse-concealing prelates from his administration, ensured that all bishops will turn abuse records over to their local police departments, and personally visited with survivors and advocates to hammer out a real plan for prevention.”

Hiner said that come February’s meeting, he hopes the pope will demand resignations of all prelates who have concealed sex crimes and direct all bishops to turn secret records and personnel files over to law enforcement officials.

Hiner also would like to see Francis direct bishops to stop spending money on lobbying efforts to kill statute-of-limitation extensions — like one that failed in Pennsylvania — that might allow victims of clergy abuse to file civil lawsuits.

This article contains information from the Associated Press.