PHILADELPHIA, PA. (CNA/EWTN News) - The Church today is called to foster among young people a sense of responsibility and enthusiasm for the Gospel mission, Pope Francis said on Saturday to group of priests and religious gathered in Philadelphia's cathedral.

Saying Mass in the Cathedral Basilica of Saints Peter and Paul Sept. 26, the Roman Pontiff said creativity is needed for inspiring young people in parishes and schools to "have the same high ideals, generosity of spirit, and love for Christ and the Church".

"Do we challenge them? Do we make space for them and help them to do their part? To find ways of sharing their enthusiasm and gifts with our communities, above all in works of mercy and concern for others? Do we share our own joy and enthusiasm in serving the Lord?"

The Pope stressed the importance of inspiring the faithful in their mission to spread the Gospel in this day in age.

"One of the great challenges facing the Church in this generation is to foster in all the faithful a sense of personal responsibility for the Church's mission, and to enable them to fulfill that responsibility as missionary disciples, as a leaven of the Gospel in our world," he said.

"This will require creativity in adapting to changed situations, carrying forward the legacy of the past not primarily by maintaining our structures and institutions, which have served us well, but above all by being open to the possibilities which the Spirit opens up to us and communicating the joy of the Gospel, daily and in every season of our life."

Saturday's Mass is the first major event of Pope Francis' visit to Philadelphia, which will culminate with his participation in the World Meeting of Families, already underway in the city. The Sept. 22-28 apostolic journey to the U.S. marks this Pope's first on American soil.

Remarking on the history of the cathedral, Pope Francis said the history of the Church in Philadelphia is not about building walls, but metaphorically "breaking them down" in bringing the faith to others.

"It is a story about generation after generation of committed Catholics going out to the peripheries, and building communities of worship, education, charity and service to the larger society."

This Catholic legacy is evidenced by the various shrines and parishes throughout the city, and two hundred years of ministry on the part of priests, religious, and lay persons in caring for the poor, immigrants, sick, and the imprisoned, the Roman Pontiff said.

He continued that it is also demonstrated in the hundreds of schools, run by religious men and women, as they "trained children to read and write, to love God and neighbor, and to contribute as good citizens to the life of American society."

"All of this is a great legacy which you have received, and which you have been called to enrich and pass on," the Pope said.

Pope Francis spoke about 19th century Philadelphia-native St. Katherine Drexel, foundress of the Sisters of the Blessed Sacrament.

He recounted a meeting she had with Leo XIII about the needs of the missions, during which the then-Pope asked her: "What about you? What are you going to do?"

"Those words changed Katharine's life, because they reminded her that, in the end, every Christian man and woman, by virtue of baptism, has received a mission," the Pope said.

"Each one of us has to respond, as best we can, to the Lord's call to build up his Body, the Church."

Pope Francis went on to reflect on the significance of these words of Leo XIII - "What about you?" -  for priests, religious, and consecrated persons in the mission of spreading the Gospel and building up the Church.

Just as these words changed the young Katherine Drexel's life, so too should those responsible for young people help foster them with a desire to do their part in serving God.

"They made her think of the immense work that had to be done, and to realize that she was being called to do her part. How many young people in our parishes and schools have the same high ideals, generosity of spirit, and love for Christ and the Church!" the Pope said.

"Do we challenge them? Do we make space for them and help them to do their part? To find ways of sharing their enthusiasm and gifts with our communities, above all in works of mercy and concern for others."

Katherine Drexel, moreover, was a lay woman when Leo XIII challenged her with the words "What about you?" - a fact Pope Francis said was significant in recognizing the role of the laity in the Church's future: "We know that the future of the Church in a rapidly changing society will call, and even now calls, for a much more active engagement on the part of the laity."

The Pope recognized the commitment of the Church in the United States to catechesis and education, and called the faithful to build upon this. He also stressed the significant role which women, both lay and religious, play in enlivening communities.

"Our challenge today is to build on those solid foundations and to foster a sense of collaboration and shared responsibility in planning for the future of our parishes and institutions," he said.

"This does not mean relinquishing the spiritual authority with which we have been entrusted; rather, it means discerning and employing wisely the manifold gifts which the Spirit pours out upon the Church."

Pope Francis went on to thank the priests and religious present for also responding to the question: "What about you?"

"I encourage you to be renewed in the joy of that first encounter with Jesus and to draw from that joy renewed fidelity and strength," he said.

In light of the World Meeting of Families, the Pope reminded the priests and religious present of their role in ministering to families, couples preparing for marriage, and young people.

"I know how much is being done in your local Churches to respond to the needs of families and to support them in their journey of faith," he said.

He called on them to pray for these families, as well as for October's Synod on the Family in the Vatican.

The Pope concluded by invoking Mary's intercession for the Church in the US to be a "prophetic witness to the power of her Son's Cross to bring joy, hope and strength into our world."

At the conclusion of Mass, Pope Francis received a greeting from Philadelphia's Archbishop Charles Chaput, who thanked him for showing support for families, marriage, immigrants, youth, and the poor. He said the entire city has awaited this visit: "Not just Catholics, but Christians from every tradition; a vibrant and generous Jewish community; our mayor and governor and business leaders who've given us wonderful support; and people of good will from every walk of life."

He also recalled how Philadelphia has produced two great saints in the United States: St. Katharine Drexel and St. John Neumann.

"Thank you for celebrating the Eucharist with us today. Thank you for showing your support for families, for marriage, for immigrants, the young and the poor. Most of all, thank you for living the Gospel of Jesus Christ with a spirit of joy that has reached into every heart in this cathedral."

Over the course of his Sept. 19-28 apostolic journey, Pope Francis visited Cuba before moving on to the United States.

Highlights of the journey have included the canonization of St. Junipero Serra and the Pope's address to the US Congress in Washington, D.C., his speech to the United Nations' headquarters in New York, and an interreligious gathering held at Ground Zero.