VATICAN CITY (CNS) -- Europe's Christians must speak with one voice to defend religious liberty and to ensure desperate migrants are treated fairly, Pope Francis said.

Only "looking together toward the Lord Jesus Christ," he said, will Christians "find common responses to the questions modern society is asking us."

Pope Francis met at the Vatican May 7 with members of a joint committee representing the Catholic Council of European Bishops' Conferences and the ecumenical Conference of European Churches.

The two organizations' collaboration, the pope said, gives "great hope for the overcoming of divisions" among Christians, even while recognizing that the path to "full and visible communion among all believers in Christ" is still long.

Even though the ecumenical task is difficult, he said, "it is an integral part of the process of reconciliation and communion which the Lord asks of us and helps us accomplish so that it would be lived in charity and truth."

Pope Francis said the witness of Christianity is harmed "when the churches and ecclesial communions of Europe present different visions on important anthropological and ethical questions." The only solution, he added, is "common reflection in the light of the sacred Scriptures and our shared tradition."

Christians in Europe "find themselves before new and decisive challenges to which we can respond effectively only by speaking with one voice," the pope said. "I am thinking, for example, of the challenge posed by legislation which, in the name of a poorly interpreted principle of tolerance, ends up preventing citizens from freely expressing and practicing their religious convictions in a peaceful and legitimate way."

But also, he said, a united voice is needed in helping the continent's nations and people respond to the needs of the poor, particularly the "dramatic and often tragic migration of thousands of people fleeing war, persecution and poverty."

Christian communities "have an obligation to collaborate to promote solidarity and welcome," the pope said. "Europe's Christians are called to intercede with their prayers and to work actively to promote dialogue and peace in the conflicts underway."