The think tank will convene a summit in December seeking solutions to the global refugee crisis.

"It is almost incomprehensible that today...Muslim extremists are torturing and killing innocent and unarmed Christian women and children," Cardinal Wuerl said.

Pope Francis will encounter a deeply emotional story of both betrayal and salvation during a somber visit Friday to the former Nazi German death camp of Auschwitz-Birkenau, where some 1.1 million people were murdered, most of them Jews.

Welcoming Pope Francis to the cathedral meeting, Archbishop Gadecki said the pope's task was to "care for the unity, wholeness and inviolability of Christ's teaching."

"I worry about his rhetoric," said the cardinal in response to the question by a reporter during an interview with Raidio Teilifis Eireann. "It's very easy to stir up resentment and to blame groups of people."

"The service was wonderful, a reminder that we are all people of God," Janet Mills, a Methodist laywoman, said. "I loved the experience. I loved the singing, especially 'Amazing Grace' and 'God Bless America.'"