KRAKOW, Poland (RNS) To outsiders, a massive rally of young Catholics waving flags and chanting “Francis” might seem like a strange spectacle far removed from today’s pressing concerns.

But in a world scarred by religiously inspired violence and grappling with a global migrants crisis, the World Youth Day gathering in Poland that wrapped up on Sunday (July 31) could be read as a powerful piece of counterprogramming.

As the weeklong event began in Krakow, the news broke that an elderly priest in France had been brutally killed by Islamic extremists while celebrating Mass.

The Rev. Jacques Hamel’s two killers were just 19 years old, a stark contrast to the young people praying and celebrating during World Youth Day events in Poland.

The assailants, who were killed by authorities near the city of Rouen after Tuesday’s slaying, used the veneer of religion to justify their acts — a hijacking of faith that was sharply denounced by Islamic leaders in Rouen and by Francis.

Many Muslims across the country even attended Mass on Sunday to show solidarity with the Catholic community.

Underscoring that example, the Catholic teenagers in Poland were treated to a powerful series of talks from Pope Francis telling them that the heart of true faith is found in love, mercy and serving society’s outcasts.

That was the core of Francis’ preaching on Saturday evening when in characteristically folksy and accessible language he urged young people to stop being “couch potatoes,” to switch off their video games and to go out and leave their mark on the world in a positive way by helping migrants, the homeless and all those discarded by the world.

But as much as the pontiff’s message, the experience of the eclectic gathering may have left a profound mark on these young people.

World Youth Day is a kind of Catholic jamboree that takes place every three years in a different country and it is an opportunity for a wide range of young people of different nationalities to mingle freely.

In Krakow, Koreans drank Polish beer in bars sitting next to Italians while American pilgrims from across the United States sang and danced in the city’s historic squares alongside groups of young nuns from around the globe.

Among the crowds were young people from Syria, a number of whom had found asylum in Europe, having fled the destruction from the civil war in their homeland. During a Saturday night prayer vigil, Rand Mittri, a 26-year-old from Aleppo, gave the pope and a crowd of 1.6 million a firsthand account of what that looked like.

“Being here changes prejudices about refugees and those who are different,” said Alessandro Bombaci, who had traveled to Poland with a parish group from Turin, in northwest Italy. “It gives you a chance to get in touch with people from all over the world and you see a different picture to how they are portrayed in the media,” said Bombaci, who had spent the night with thousands of others in a “Mercy Camp” near the site of the Mass.

A day earlier Francis had highlighted that lesson, telling the young people that Christianity’s credibility is measured on how it treats outcasts, including those refugees seeking a better life in Europe.

But Francis also knows that the forces of division and rejection are strong even within his own church, and often within a hierarchy that is far removed from the lives of the young people.

Poland, for example, which remains overwhelmingly Catholic and was the birthplace of the renowned 20th-century pontiff, St. John Paul II, is currently run by a right-wing government that is hostile to refugees, particularly those from countries like Syria.

“Those who criticize Poland for not bringing in immigrants will probably say: Pope Francis came and lectured Poland,” Prime Minister Beata Szydlo said as the visit ended, adding that the country had welcomed large numbers of Ukrainian migrants and sent aid to the Middle East.

Tensions between Francis and the government were further complicated by the enduring alliance between the state and a church that is seen as equally conservative. While Catholicism is praised for opposing fascism and Communism — stands epitomized in John Paul’s efforts in ending the cold war — the church has a strong hold in society that some view as outdated.

Francis could be among them.

The pope and the Polish bishops have clashed over the Argentinian pontiff’s efforts to instill a more pastoral approach that includes welcoming divorced, remarried and other Catholics who rules say should be barred from Communion. During the papal visit the country’s leading churchman, Archbishop Stanislaw Gadecki, said the Polish church would refuse to bend on those doctrines.

Keen to avoid public disagreement, the pope and the bishops met in private for an “informal dialogue” where no speech was delivered: This contrasted with papal visits to the United States and Mexico where Francis used speeches to upbraid the country’s hierarchies in an effort to get them to change their approach.

The real focus for Francis in Poland, however, was not so much the internal political wrangling with the church and the government, but the broader challenges facing religion and the world.

At the final Mass on Sunday, Francis urged the young people to “believe in a new humanity,” one that refuses to see borders as barriers; where traditions can be cherished but “without being self-centered or small-minded.”

This was a rallying cry to demonstrate that religion, so often blamed for the world’s problems, can be a force for good and can mobilize young people to help others. That includes all religions.

“I do not like to speak of Islamic violence, because everyday when you read the newspapers you see violence,” Francis told reporters on the plane back to Rome late Sunday.

In Italy as well, he said, you see terrible murders. “These are baptized Catholics,” Francis said, according to a transcript by National Catholic Reporter. “They are violent Catholics. If I speak of Islamic violence, I have to speak of Catholic violence. Not all Muslims are violent. Not all Catholics are violent.”

“This is a small fundamentalist group that is called ISIS,” he said. “You cannot say — I believe it is not true and it is not just — that Islam is terroristic.

“Terrorism grows when there is not another option, and while at the center of the global economic system there is the God of money and not the person, man and woman.”

World Youth Day certainly has a track record of inspiring Catholics to take their faith more seriously: Cardinal Sean O’Malley, the archbishop of Boston, said that a third of the current trainee priests in the U.S. have been to at least one of the gatherings. Others are known to meet their future spouses at World Youth Days or to discern a call to be a monk or nun as a result of the experience.

“One of the most impactful things about coming here is that you really see the ‘Catholic’ Church, it’s multi-nationality — and that’s inspiring,” Gabriel Luke Mary, 32, a seminarian for the Diocese of Pittsburgh, said. “The question is whether parishes will be able to cultivate what is planted here, or will it be choked?”

(Christopher Lamb is a Rome-based correspondent covering the papal trip for RNS)