The pope arrives at the 9/11 memorial site to lead a multi-religious service on Sept. 25. (Reuters)

Pope Francis will descend Friday into the lower level of the Ground Zero museum, and into the dark story of Sept. 11 for an interfaith ceremony organizers hope will present religion as a force for tolerance at a time of disturbing religious violence.

The ceremony in the late morning, after Francis has spoken to the United Nations, was dramatically set in the soaring Foundation Hall, against a World Trade Center retaining wall that stayed up despite the attacks.

The choice of the spot in the 9/11 Memorial’s museum represents a “new urgency” for religious tolerance, said James Massa, a Brooklyn bishop who has been a national Catholic leader on interfaith work and who designed the ceremony.

[Live coverage: Pope Francis in New York]

“That’s the wall that holds back the Hudson River. If that had fallen on 9/11, even greater chaos would have happened. It held. It’s the wall that holds back the chaos. I think these leaders with the pope are gathered, like the conscious of our time, that holds back the chaos of war and violence and hatred that afflict segments of humanity,” Massa said.

Francis selected Ground Zero as the place in the United States he wanted to have an interfaith gathering, Massa said. Pope Benedict visited Ground Zero and prayed there in 2008 but the memorial and museum were not yet built.

Other spiritual leaders who would be at the event said they felt Francis has unique stature at a time when people are losing faith in institutional religion, which is in turn splintering as a societal structure.

Some are investing a huge amount in the visit of Francis.

[Here’s the program for the 9/11 service]

“To be able, on that spot, to have a service with interfaith leaders, and this pope, to try and figure out: How do we craft a world where religion is the glue that holds our moral fiber together — not this battering ram of ideology and ethnocentrism and hatred” said Rabbi Rick Jacobs, president of Judaism’s largest denomination, the Reform movement. “I can’t help but think, what would the experience of World War II have been if Pope Francis had been pope? What would have been if the moral voice coming from the Vatican would have been this pope’s voice? He wouldn’t have erased World War II but I know many more of my people and those persecuted by Nazis would have not only fared better, but survived.”

Speaking to New Yorkers of different faiths at the 9/11 memorial, the pope mourned the "unspeakable violence and pain" of Sept. 11, 2001, and called for healing for all victims and survivors. Pope Francis prayed to turn the hearts of those who "justify killing in the name of religion" and called for peace among nations. (Reuters)

Francis has made symbolically powerful efforts on behalf of interfaith, from a book he wrote with his close friend, the Argentine Rabbi Abraham Skorka, to washing the feet of a female Muslim prisoner shortly after taking office. He has apologized to Italian Pentecostals who were persecuted in the past by Catholics. He let a friend shoot an iPhone video message back to some American evangelists, who he said he spoke to “as a brother.” Of course it went viral.

To Congress Thursday, he described the world as “increasingly” a place of violent conflict and hatred, including in the name of God – but warned of the response. “We know that in the attempt to be freed of the enemy without, we can be tempted to feed the enemy within.” He praised in the talk Catholic mystic Thomas Merton, a writer who explored Eastern faiths and had “a capacity for dialogue and openness to God.”

Francis’s theology is mainstream for the church today, but with this pope everything packs a more powerful punch because of his personality and spontaneity.

In fact the Catholic Church set off massive changes 50 years ago this fall with the Second Vatican Council document called Nostra aetate. That opened in a dramatic way Catholics to other faiths. Because of the size of the church, that was the first domino for many other faith groups to begin dialogue and study together that before had been seen by many as forbidden.

Catholics were not allowed into other places of worship before then. “Before the Council, the language referring to other Christians as ‘heretics’ and practitioners of other faiths as ‘infidels’ — that was the language of preaching and catechesis,” Massa said.

Change came quickly, but even by the 1980s it was considered controversial when Pope John Paul held World Day of Prayer in Assisi, Italy, where some rejected the idea of clergy who believed in different concepts of God – and different paths to God – worshipping together. To whom were they equally praying?

Interfaith today faces many of the same issues – and new ones. Massa noted that the service was being described as “multi-faith,” not interfaith “as we have to careful that our religious identities are preserved.” The term “multi-faith” isn’t praying together “in the strict sense, but in the presence of the other.”

Another challenge for the interfaith movement is that younger people who are surrounded by mixed-faith couples and parents may not see the need for inter-religious dialogue and work because they feel they are living it. Or perhaps they feel people involved in such work are only having feel-good, time-wasting conversations.

But religious tensions around the world and in the United States, Jacob said, show the topic is urgent.

“It’s not just the pope’s piece of this puzzle but the larger interfaith movement turns on questions of theological pluralism. There is more than one way to live a life of deep faith,” he said.

Religion has “undergirded so much of the strife.. This has been underpinning of the unraveling of the world. Interfaith is to provide a different underpinning,” Jacobs said.

The massive Foundation Hall was a contrast Friday: The stained, rough grey concrete of what they call the Slurry Wall and the 36-foot high, graffiti-covered final column – which was the last steel beam removed from the wreckage site – as the backdrop to rows of crisp white chairs, ushers in white gloves and tails and elegantly clad guests.

More than 400 representatives of dozens of faith communities were invited to the 75-minute gathering, called “A Witness to Peace.” It will include a prayer from the pope and “meditations on peace” from Hindu, Sikh, Muslim, Christian, Buddhist leaders as well as a traditional Jewish prayer for the dead, the El malei rachamim, which is chanted and calls for the ascension of the souls of the dead.

The service ends with the Young People’s Chorus of New York City singing “Let There Be Peace On Earth.”

After the ceremony, Francis was to visit two faith relics at the museum. Two steel beams in the shape of a Christian cross, often called “The Ground Zero Cross”, that were found in the wreckage became a destination after the 2001 attacks. Eventually weekly Sunday Mass was held for years there, with a sign “All are welcome.” The pope will also see a New Testament found in the wreckage, fused to a piece of metal. It is permanently open to Matthew 5:39: “But I say to you, ‘Do not resist one who is evil.’ But if any one strikes you on the right cheek, turn to him the other also.”

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