Updated

Pope Francis called for structural renewal in the Catholic church to keep up with the times, although he counseled future priests and nuns Saturday to shun costly trappings like the latest smartphones and fancy cars so they can devote more resources to help the poor.

Francis has been waging a campaign to root out corruption and power plays in the Vatican's bureaucracy and to keep sight of what is essential in the church he was elected in March to lead. His remarks in two appearances Saturday drew on his determination to forge what he likes to call a "poor church."

The Argentine-born pontiff offered the encouragement for renewal in a homily during Mass Saturday at the Vatican City hotel where he lives. Francis told Catholics "not to be afraid of renewing some structures" to accord with "the places, the times" and the people, but he didn't specify what needed to be changed.

He said, "In Christian life, even in the life of the church, there are ancient structures, transient structures: It is necessary to renew them!"

Later, he gave an off-the-cuff lecture to a Vatican auditorium full of seminarians and novices, and to thunderous applause, told the future priests and nuns to keep "freshness" and "joy" in their lives. He took to task seminarians and novices who "are too serious, too sad."

"Something's not right here," Francis told his rapt audience.

"There is no sadness in holiness," he added, saying that such clergy lack "the joy of the Lord."

"If you find a seminarian, priest, nun, with a long, sad face, if it seems as if in their life someone threw a wet blanket over them," then one should conclude "it's a psychiatric problem, they can leave — 'buenos dias,'" Francis said, choosing his words slowly as he went along, ignoring a prepared speech in his hand.

He reminded the future priests and nuns that he wasn't talking about superficial joy — "the thrill of a moment doesn't really make us happy." He warned against seeking "the joy of the world, the latest smartphone, the fastest car."

"It hurts my heart when I see a priest or a nun with the latest model of car," Francis said, then quickly joking that his audience will think "now, we'll have to go around on bicycle."

"Cars are necessary. But take a more humble one," said Francis, who from the day he took office declined to move out of the hotel during the conclave of cardinals and into the ornate Apostolic Palace that is the traditional home to pontiffs. "Think of how many children die of hunger" and dedicate the savings to them, Francis said.

At one point he turned to an aide and asked how much time he had with the young future priests and nuns. Told that he could stay there "until tomorrow" if he wanted, Francis joked to his audience that they would need "sandwiches and Cokes if we go till tomorrow," drawing roars of laughter. In the end, he spoke for about an hour with the seminarians and novices, and will celebrate Mass which they will attend in St. Peter's Basilica on Sunday morning.

During his remarks, Francis praised the late Mother Teresa, who cared for the most impoverished sick of Calcutta, India, and held her up as a courageous example. "I would like a more missionary church," the pope then told the young people, who seemed to hang on his every word. "Not so much a tranquil church, but a beautiful church that goes forward."

His praise of Mother Teresa will likely be seen as an indication that Francis will be eager to have her made a saint.

On Friday, the Vatican announced that Francis had decided to canonize two predecessors, John Paul II and John XXIII, even though the usual requirement of a second miracle attributed to John XXIII's intercession hadn't been certified. Bestowing sainthood on John Paul II, who died in 2005, puts him on a much faster path to canonization than Mother Teresa, who died in 1997.