VATICAN CITY (CNS) -- Welcoming thousands of migrants and refugees to the Vatican for their own Year of Mercy celebration, Pope Francis urged them to resist everything that would rob them of hope and joy.

"Each of you is the bearer of a history, culture and precious values and, unfortunately, also often of experiences of poverty, oppression and fear," the pope said Jan. 17. But gathering in St. Peter's Square for the Holy Year "is a sign of hope in God. Don't allow yourselves to be robbed of hope and the joy of living, which spring from the experience of divine mercy, also thanks to the people who welcomed and helped you."

The pope prayed that passing through the Holy Door and attending a special jubilee Mass "will fill your hearts with peace." He also thanked the inmates of a maximum security prison in Milan who prepared the hosts consecrated at the Mass.

According to the Italian news agency, ANSA, an estimated 7,000 migrants from 30 countries were present. The group passed through the Holy Door of St. Peter's Basilica, following a 9-foot tall, 3-foot wide wooden cross made out of the wreckage of boats carrying migrants from northern Africa to Lampedusa, Italy's southernmost island.

The Mass was celebrated by Cardinal Antonio Maria Veglio, president of the Pontifical Council for Migrants and Travelers, who said in his homily that the cross was "an expressive symbol" of the tragic circumstances facing migrants who risk their lives seeking a better future.

The World Day of Migrants and Refugees, he said, was "a fitting occasion to remember that the church has always contemplated in migrants the image of Christ. Moreover, in the Year of Mercy, we are challenged to rediscover the works of mercy where, among the corporal works, there is the call to welcome the stranger."

The presence of migrants is a visible sign of the universality of the church and the integration of newcomers is not about "assimilation" but an opportunity to recognize "the cultural patrimony of migrants" for the good of the universal church.

"Everyone has something new and beautiful to contribute, but the source and steward is the Spirit," he said. "No one should feel superior to the other, but all must realize the need to collaborate and contribute to the good of the sole family of God."

Recalling Pope Francis' message for the World Day of Migrants and Refugees, Cardinal Veglio compared the plight of migrants to the Holy Family exiled in Egypt, which serves as a reminder that the "welcoming of the stranger means welcoming God himself."