Pope Francis visited a refugee camp in Bulgaria Monday and told migrants that they have become “humanity’s cross” to bear.

“Thank you so much for your welcome. Thanks to the children for their beautiful singing. They bring joy to your path,” the pope told the mostly Syrian and Iraqi residents of the Vrazhdebna camp in the outskirts of the Bulgarian capital of Sofia.

“Your path is not always beautiful, and then there is the sorrow of leaving your homeland and trying to fit into another homeland. There’s always hope,” he said in his brief greeting.

“Today the world of migrants and refugees is a bit of a cross, humanity’s cross, the cross that so many people suffer,” he said. “I thank you for your goodwill and I wish the best for you and your fellow countrymen that left back in your homeland. God bless you and pray for me.”

Francis began his three-day apostolic Balkan visit on Sunday, arriving in Sofia in the morning, where he lamented Europe’s low birthrate and urged his hosts to open their hearts to migrants.

The pope has made immigration a central theme of his 6-year pontificate, often encouraging world leaders to open their hearts and their countries to migrants.

Last week, Francis denounced a growing nationalist movement, saying it entails “excessive demands for sovereignty” and is often marked by hostility toward migrants.

“The common good has become global and nations must associate,” the pope told members of the Pontifical Academy of Social Sciences who gathered in the Vatican for their annual meeting, entitled “Nation, State, Nation-State.”

“The Church observes with concern the re-emergence, in many parts of the world, of currents that are aggressive towards foreigners, especially immigrants, as well as a growing nationalism that neglects the common good,” he said.

The pope said that “the way in which a nation welcomes migrants reveals its vision of human dignity and of its relationship with humanity.”

“When a person or family is forced to leave their land, they must be welcomed with humanity,” he added.

“The migrant,” Francis continued, “is not a threat to the culture, customs and values ​​of the receiving nation.”

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