VATICAN CITY (RNS) In his annual Christmas address to the Vatican bureaucracy, Pope Francis on Thursday (Dec. 22) warned that those engaged in “malicious resistance” to the reform of the Roman Curia are inspired by the devil.

It marked the third consecutive year that the pope has slammed the highest levels of the Catholic Church’s administration in his annual holiday greeting at the Vatican.

In his address this year, Francis urged the prelates who work with him to undergo "permanent conversion and purification" to modernize the church and serve it better.

“Without a change of mentality, efforts at practical improvement will be in vain,” he said.

Francis said the reforms had understandably prompted instances of "open resistance" and "hidden resistance," both of which could be constructive and a sign of life if done with good intentions.

Then, he said, "there are also cases of malicious resistance, which spring up in misguided minds and come to the fore when the devil inspires ill intentions (often cloaked in sheep’s clothing)."

"This last kind of resistance hides behind words of self-justification and often accusation," he said. "It takes refuge in traditions, appearances, formalities, in the familiar, or else in a desire to make everything personal, failing to distinguish between the act, the actor and the action."

The 80-year-old pontiff warned his audience that the administrative reforms he has begun would be far-reaching and required profound change among those who run the Vatican Curia or administration.

"Dear brothers, it's not the wrinkles in the church that you should fear, but the stains!" he said.

The pope gave the priests, bishops and cardinals who work for him 12 guidelines that are inspiring his reforms.

Francis also gave them a copy of “Curing the Illnesses of the Soul,” a book written by an Italian Jesuit priest, the Rev. Claudio Acquaviva, who died in 1615.

The pope wants to promote modernization and called for the Vatican to employ more women and more laypeople and to reflect a multicultural society.

In one of his strongest messages he called for an end to the Vatican's way of getting rid of unqualified or unwanted staff, known as "promote and remove."

"This is a cancer!" Francis said.

In 2014, Francis shocked the Curia when he listed the 15 "spiritual ailments" he believed were afflicting its members and accused them of hypocrisy.

He said many were pursuing their careers for power and wealth and suffering from a type of "spiritual Alzheimer's" instead of serving God.

Last year, Francis listed a "catalog of virtues," including honesty, sobriety, respect and humility.

(Josephine McKenna covers the Vatican for RNS)