Pope Francis on Friday encouraged Christian Koreans to be leaven in their society, asking them to embrace the "true freedom" of loving God and one another with "a pure heart."

"May the Christians of this nation be a generous force for spiritual renewal at every level of society. May they combat the allure of a materialism that stifles authentic spiritual and cultural values and the spirit of unbridled competition which generates selfishness and strife," the Pope told tens of thousands of people gathered for Mass in the World Cup Stadium in the city of Daejeon.

"May they also reject inhumane economic models which create new forms of poverty and marginalize workers, and the culture of death which devalues the image of God, the God of life, and violates the dignity of every man, woman and child," he said in his Aug. 15 homily.

Pope Francis said that Korean Catholics are "heirs to a noble tradition" and are "called to cherish this legacy and transmit it to future generations."

"This will demand of everyone a renewed conversion to the word of God and a passionate concern for the poor, the needy and the vulnerable in our midst," he said.

The Pope's homily came during Mass for the Solemnity of the Assumption of the Blessed Virgin Mary.  The solemnity marks God's taking up into heaven of the Virgin Mary, body and soul.

Pope Francis said that the Virgin Mary's Assumption "shows us our own destiny as God's adoptive children and members of the body of Christ."

"Like Mary our Mother, we are called to share fully in the Lord's victory over sin and death, and to reign with him in his eternal kingdom," he said.

The Pope said that the Virgin Mary is the "Mother of the Church in Korea." He noted that Koreans traditionally celebrate the Assumption "in the light of their historical experience, seeing the loving intercession of Our Lady at work in the history of the nation and the lives of its people."

The Pope also discussed the reading from St. Paul's Letter to the Corinthians, saying that it taught that Christ's obedience to God the Father "has overturned the reign of sin and bondage and inaugurated the reign of life and freedom."

"True freedom is found in our loving embrace of the Father's will. From Mary, full of grace, we learn that Christian freedom is more than liberation from sin. It is freedom for a new, spiritual way of seeing earthly realities. It is the freedom to love God and our brothers and sisters with a pure heart, and to live a life of joyful hope for the coming of Christ's Kingdom."

Pope Francis said that Catholics look to Mary as "our Mother of Hope."

"In her, all God's promises have been proved trustworthy."

He said the hope of the Gospel is "the antidote to the spirit of despair that seems to grow like a cancer in societies which are outwardly affluent, yet often experience inner sadness and emptiness."

"Upon how many of our young has this despair taken its toll! May they, the young who surround us in these days with their joy and confidence, never be robbed of this hope!"

Pope Francis asked the Virgin Mary to guide efforts to "transform the world in accordance with God's plan" and to enable the Church in South Korea to be "ever more fully a leaven of his Kingdom in the midst of Korean society.

After the Mass, Pope Francis prayed the Angelus with those gathered together in the stadium.

In his pre-Angelus remarks, Pope Francis invoked Our Lady, Queen of Heaven and entrusted to her those who died in the Sewol ferry disaster earlier this year.

"May the Lord welcome the dead into his peace, console those who mourn, and continue to sustain those who so generously came to the aid of their brothers and sisters," the Pope said Aug. 15. "May this tragic event which has brought all Koreans together in grief confirm their commitment to work together in solidarity for the common good."

The 480-foot ferry Sewol capsized and killed 300 passengers in May while en route to Jeju Island south of the Korean mainland. Many of the victims were high school students on a field trip. The ferry disaster caused widespread sadness across South Korea and has provoked social and political tensions.

The Pope also asked the Virgin Mary to "look with mercy on all those among us who are suffering, particularly the sick, the poor and those who lack dignified employment."

The Solemnity of the Assumption of the Blessed Virgin Mary falls on the same date that South Korea celebrates its independence from Japan following World War II.

Pope Francis referred to the independence celebration in his remarks, asking the Virgin Mary "to watch over this noble nation and its citizens."

He also commended to the Virgin Mary's care "all the young people who have joined us from throughout Asia."

"May they be joyful heralds of the dawn of a world of peace in accordance with God's gracious plan!" the Pope prayed.