ROME — Pope Francis has extolled the contribution migrants and refugees make to society while urging a more welcoming spirit toward foreigners.

History “teaches us that the contribution of migrants and refugees has been fundamental to the social and economic growth of our societies. This continues to be true in our own day,” the pontiff wrote in his annual message for the World Day of Migrants and Refugees, released by the Vatican Thursday.

“Their work, their youth, their enthusiasm and their willingness to sacrifice enrich the communities that receive them,” he continued, and this contribution could be even greater if “supported by carefully developed programs and initiatives.”

In his message, the pope also pointed to the biblical image of the new Jerusalem, a borderless city where all are welcome, where the inhabitants “always keep the gates of the city wide open, so that foreigners may come in, bringing their gifts.”

The presence of migrants and refugees “represents a great challenge, but at the same time an immense opportunity for the cultural and spiritual growth of everyone,” Francis wrote. “Thanks to them, we have the chance to know better our world and its beautiful diversity. We can grow in our common humanity and build together an ever greater sense of togetherness.”

Welcoming migrants creates “spaces of fruitful exchange between different visions and traditions,” he wrote, and “leads to a discovery of the richness present in other religions and forms of spirituality.”

In an appeal addressed especially to young people, Francis exhorted: “If we want to cooperate with our heavenly Father in building the future, let us do so together with our brothers and sisters who are migrants and refugees. Let us build the future today!”

“We cannot leave to future generations the burden of responsibility for decisions that need to be made now, so that God’s plan for the world may be realized and his Kingdom of justice, fraternity, and peace may come,” he asserted.