KRAKOW, Poland—Addressing a vast sea of young women and men gathered in Krakow for World Youth Day (WYD), Pope Francis told them not to be deterred by those who want to present the image of an insensitive God, and to believe in the power of God’s mercy.

“People will try to block you, to make you think that God is distant, rigid and insensitive, good to the good, and bad to the bad. Instead, our heavenly father ‘makes his sun rise on the evil and on the good,’” Francis said on Sunday.

The pope was addressing some two million women and men gathered in Campus Misericordiae, a field set up for the occasion in the outskirts of Krakow, Poland.

Most of the pilgrims had spent the previous night in the field, some nine miles outside the city. Hundreds of thousands arrived throughout Saturday afternoon, carrying backpacks and sleeping bags, after a hot trek.

They remained there all night, following a prayer vigil led by Francis in which he urged them not to be “couch potatoes” but to instead wake up and take ownership of their own life. If not, he warned, other people — “not necessarily better” — would make decisions for them.

Before Francis’ arrival, in a 100-yard-long altar area in Campus Misericordiae, several dozen Catholic artists were in charge of waking the young up after a night spent outside.

Israeli artist Noa, with a stunning performance of the Ave Maria, was the soundtrack during much of Francis’ long ride in the popemobile through the vast field.

In his homily, Francis returned to the previous night’s theme, warning against the “paralysis of shame” and telling the pilgrims that God expects from them “real courage,” meaning a bravery that defeats evil by loving everyone, “even our enemies.”

“People may laugh at you because you believe in the gentle and unassuming power of mercy. But do not be afraid,” Francis said, using an iconic phrase associated with St. John Paul II.

Reminding the young of the motto for WYD, “Blessed are the merciful, for they will receive mercy,” the pope urged the young not to be deterred by those who are wary of them for being dreamers.

“People may judge you to be dreamers, because you believe in a new humanity, one that rejects hatred between peoples, one that refuses to see borders as barriers and can cherish its own traditions without being self-centered or small-minded,” Francis warned.

He went on to insist on the call to be merciful to those in need, highlighting the suffering of migrants and refugees.

Together with Hungary, Poland is the European country most determined to close its borders to immigrants coming from Africa and the Middle East fleeing war, persecution, hunger, and violence.

But WYD this week caused the idea of reinforcing borders to dissolve in the mix of pilgrims from Syria and Iraq, brothers and sisters in the faith at one with Poles and Hungarians.

For one week, liberal, conservative and traditionalist Catholics put differences aside to shared liturgies and prayers in harmonious coexistence.

For one week, the streets of Krakow, a deeply Catholic city, with over 300 churches, became a mirror of the Universal Church. A glimpse of a united Christianity was visible, too, as Russian Orthodox and Pentecostal pilgrims joined Catholics in the festivities.

A peek into one of the many churches offering permanent Eucharistic adoration during these days showed youngsters from Ukraine and Russia — whose nations are at war — praying together.

Mexican and American pilgrims shared boat rides along Krakow’s river, Argentines and Brazilians shared pep-rallies, and nuns and priests twirled together.

On Sunday, the ‘Mercy Field’ spectacularly illustrated that togetherness. Like a medieval battlefield, it was a sunlit sea of national flags under a clear sky, yet here the people were at peace with each other.

Perhaps nothing symbolized this more than to see Israeli and Palestinian flags mixed in with each other.

As the pope put it on Saturday’s prayer vigil, situations that would typically seem distant, “because we see them on the screen of a cell phone or a computer,” became a reality for many this week.

The long homily Francis delivered on Sunday was an epic pep-talk aimed at young people in a world that can too often give them reasons for paralysis and fear.

Reflecting on the Gospel passage that presents the story of Zacchaeus, a tax collector, a “sinner”, who climbed over a tree to catch Jesus’ attention as he was passing through Jericho, the pope spoke of the “three obstacles” the man of the parable had to overcome.

The first one, Francis said, was his “smallness of stature.” Even today, he continued, “we can risk not getting close to Jesus because we don’t feel big enough, because we don’t think ourselves worthy.”

This he said, is a great temptation related not only to self-esteem (something many teenagers lack), but to lack of faith.

Our “‘real ‘stature,’ our spiritual identity” is that “we are God’s beloved children always,” Francis said. Not being self-accepting, leading a grim-faced or negative life, was a failure to recognize this.

“God loves us the way we are, and no sin, fault or mistake of ours makes him change his mind,” the pope said. “As far as Jesus is concerned – as the Gospel shows – no one is unworthy of, or far from, his thoughts. No one is insignificant.”

In God’s eyes, the pope told the young, people are not defined by possessions or clothes or looks.

“In his eyes,” Francis told the captivated audience, “you are precious, and your value is inestimable.”

God, he said, “is always ‘cheering us on,’” he said, “he is our biggest fan.”

The second obstacle Zacchaeus faced, according to Francis, was the “paralysis of shame.”

“Zacchaeus was a public figure, a man of power. He knew that in trying to climb that tree he would have become a laughing stock to all. Yet he mastered his shame, because the attraction of Jesus was more powerful,” he said.

The tax collector put “his life on the line” and this, Francis continued, is the secret of joy: “not to stifle a healthy curiosity, but to take a risk, because life is not meant to be tucked away. When it comes to Jesus, we cannot sit around waiting with arms folded; he offers us life – we can’t respond by thinking about it or ‘texting’ a few words!”

As he often does, he invited the young to go to confession, and not to be ashamed of bringing their weaknesses, struggles and sins.

Say yes to God, Francis said, and a firm no to “the narcotic of success at any cost and the sedative of worrying only about yourself and your own comfort.”

The third obstacle Zacchaeus had to face was the “grumbling of the crowd” who blocked him because he was a sinner. Here, he said, it was important to resist the images of an insensitive God, and to believe in the unassuming power of his mercy.

Picking up on a major theme this week of memory, he finally urged the pilgrims to “trust the memory of God.”

“His memory is not a ‘hard disk’ that ‘saves’ and ‘archives’ all our data, but a heart filled with tender compassion, one that finds joy in ‘erasing’ in us every trace of evil,” he said.

As he finished his homily by leading some minutes of silent prayer, a great stillness fell on the vast assembly.