LIMA, Peru – When a pope decides to take up a fight, he can deploy many legions, from front-line pastors around the world to his own prelates, diplomats and experts in Rome. No pope, however, enters a fight exclusively on the visible field of battle, because he’s also counting on the quiet support of spiritual warriors storming Heaven with prayer.

Pope Francis on Sunday met with a group of those unseen warriors, in the form of contemplative women religious, and urged them to keep pressing the spiritual battle against what he calls a “throw-away” culture.

Calling contemplatives to a spirit of “missionary prayer,” Francis urged them to see their role as every bit as important to the activists and charity workers who engage in direct outreach to the poor, suffering and marginalized.

“You pray and intercede for our many brothers and sisters who are prisoners, migrants, refugees and victims of persecution,” Francis said, quoting a document on women’s contemplative life he issued in 2016.

“Your prayers of intercession embrace the many families experiencing difficulties, the unemployed, the poor, the sick, and those struggling with addiction, to mention just a few of the more urgent situations,” the pope said.

A life of prayer, Francis said, hardly means detachment from the challenges of the world.

“Cloistered life neither closes nor shrinks our hearts, but rather widens them in our relationship with the Lord, making them capable of feeling in a new way the pain, the suffering, the frustration and the misfortune of so many of our brothers and sisters who are victims of today’s ‘throwaway culture,’” the pontiff said.

The term “contemplative” in Catholic religious life generally refers to both communities and individuals who have devoted themselves almost entirely to a life of prayer, as opposed to active service in the world, with that life often unfolding behind closed doors in what’s known as a “cloister.”

Francis made a joking reference to that practice on Saturday, looking around at the outdoor gathering and saying, “I have a bad thought … You took advantage [of this event] to leave the convent and take a little stroll.”

The pontiff also sent a greeting to four Carmelite convents in Buenos Aires, saying he wanted to put them at the feet of Peru’s Lord of Miracles too, because they accompanied him with prayer during his ministry.

“You won’t get jealous, right?” he asked the nuns who were with him, drawing laughs and applause.

From the beginning, the idea of a “throwaway culture” has been one of the signature phrases of Francis’s papacy, a shorthand way of referring to what he regards as a brutal 21st century culture in which whole categories – including the unborn, the elderly, the poor, and even the earth itself – are essentially regarded as disposable.

Francis generally contrasts the “throwaway” culture with what he calls a “culture of encounter,” or “welcome,” meaning a culture in which people are treated with dignity and the earth with respect. In many ways, one could say that the defining battle of his pontificate is precisely the struggle against the “throw-away culture.”

On Sunday, Francis told the contemplatives they play a key role in that effort.

“Missionary prayer makes us one with our brothers and sisters in whatever situations they find themselves, and asks that love and hope will never fail them,” he said, always standing “alongside the suffering of so many of our brothers and sisters.”

In fact, Francis said, part of the mission of the contemplative is to ask God for things on behalf of people who can’t do the asking themselves.

“You are like those who brought the paralytic to the Lord for healing. Through your prayer, night and day, you bring before God the lives of so many of our brothers and sisters who for various reasons cannot come to him to experience his healing mercy, even as he patiently waits for them,” he said.

“By your prayers, you can heal the wounds of many,” he said.

Francis also urged the contemplatives to pray for the unity of the church in Peru.

In an extemporaneous flourish at the end, the pope told the nuns the Church doesn’t “tolerate you, it needs you!”

“Be beacons of light,” he said. “And pray for the Church, for the shepherds, for those who hurt others, and those who exploit their siblings. And going on with the list of sinners, don’t forget to pray for me.”

Sunday is the pope’s final day in Peru. Later, he’ll address the country’s bishops, deliver an Angelus address, and celebrate Mass at an air base before boarding his plane for the return flight to Rome.

En route, Francis is expected to hold his customary press conference with journalists covering the trip.