Pope Francis warned priests studying to serve in the papal diplomatic corps and the Vatican's Secretariat of State not to be career-driven and end up looking ridiculous.

"Please don't be ridiculous, either be saints or go back to the diocese and be a pastor, but don't be ridiculous in the diplomatic service, where there is so much danger of becoming worldly in spirituality," Pope Francis said June 6.

When there is a secretary or a nuncio that doesn't strive for sanctity, the pontiff added, he "gets involved in so many forms, in so many kinds of spiritual worldliness" and "he looks ridiculous, and everyone laughs at him."

In his address to 45 members of the Pontifical Ecclesiastical Academy in the Clementine Hall, he also warned against focusing on their service as a career and trying to climb the ranks.

"This freedom from ambition or personal aims, for me, is important, it's important!" he exclaimed.

"Careerism is leprosy! Leprosy! Please, no careerism!" he pleaded.

The academy trains priests to be official representatives of the Pope. The intensive formation process takes four years: two earning a licentiate in canon law and two obtaining a doctorate in canon law.

They also learn diplomatic history, multiple languages and diplomatic writing, as well as other practical skills needed to work as an official papal emissary.

The Pope emphasized to the students that they are being prepared for a ministry, not a profession.

"This ministry calls you to go out of yourself, to a detachment from self that can only be achieved through an intense spiritual journey," he said.

He explained it also involves "a serious unification of your life around the mystery of the love of God and of the inscrutable plan of his call."

Pope Francis then asked them to cultivate their spiritual life for the inner freedom that is necessary for their careers.

"The work that is done in the pontifical diplomatic service requires, like any type of priestly ministry, a great inner freedom."

"It means being free from personal projects, from some of the concrete ways in which perhaps one day you had thought of living your priesthood," he stated.

The pontiff added it also means being free from the possibilities of "planning for the future, from the perspective of remaining for a long time in a 'your' place of pastoral action."

And "above all, it means vigilance in order to be free from ambition or personal aims, which can cause so much harm to the Church."

Being free, he counseled, means trying not to put first "your own self-fulfillment or the recognition that you could get," but rather "the greater good of the cause of the Gospel."

"It means freeing yourself, in some way, even with respect to the culture and mindset from which you came," said the Pope.

"Not by forgetting it, much less by denying it, but by opening yourself up, in charity, to understanding different cultures and meeting with people even from worlds very far from your own."

The Holy Father also advised the future diplomats to take "great care" of their spiritual life, which he called the "source of inner freedom."

"Without prayer, there is no interior freedom," the Pope remarked.

He told them to "cultivate a life of prayer" and make their daily work their "gymnasium of sanctification."

"Diplomacy should always be permeated by a pastoral spirit, otherwise it counts for nothing and makes a holy mission ridiculous," he remarked.

"I ask you to pray for me … may the assurance of my prayers and of my blessing, which I cordially extend to all your loved ones, go with you," he finished.