(RNS) — Forty years ago, Alex Kronemer was a bored college student on a semester-abroad tour of Italy when he entered what felt like his millionth Catholic church.
Thinking to sneak away, he headed for the exit. There, by the main door, was an exquisite Giotto fresco depicting St. Francis of Assisi undergoing trial by fire before the sultan of Egypt.
Kronemer stopped in his tracks.
"It immediately captured my imagination," he said of the fresco, which shows Francis defiant before a chest-high pillar of flame that arises at the command of the enthroned sultan.
"It stayed with me," Kronemer added, because he always felt that there was more to this particular saint than "just the guy who loved animals."
Francis of Assisi and the Sultan of Egypt risk it all to end the Crusades.
The film, narrated by Academy Award winner Jeremy Irons, recounts the unlikely friendship between Francis and Malik al-Kamil Nasir al-Din Muhammad, ruler of Egypt and nephew of the great Muslim leader Saladin.
The Italian saint — whom Pope Francis is named after — traveled to Egypt in 1219 to preach against war among the Christian Crusaders. He arrived as tens of thousands of Christian soldiers besieged the Muslim fortress of Damietta, defended by Sultan Malik al-Kamil.
The story goes that Francis crossed the battle lines and made his way to the sultan's camp. He told the sultan he wanted to preach the Gospel to save his and his companions' souls — and the sultan, who could have killed him as his enemy, instead received him graciously.
Francis offered to walk through fire — the inspiration for the Giotto fresco — to demonstrate the truth of the Gospel, but the sultan declined. He allowed Francis to preach to his court.
The two men spent several days together, eating together, talking together, before Francis returned to the Christian side of the battlefield. Scholars depict the encounter as pivotal for Francis.
"I believe in watching Muslims pray, men and women, five times daily that it really struck Francis unexpectedly," Michael Cusato, a Franciscan priest and historian, says in the film. "I think it profoundly moved him."
Kathleen Warren, a Franciscan sister, adds, "The respect they had for each other spoke volumes to Francis that this, indeed, was not an enemy, this was not a beast, but this truly was a brother."
But the Crusaders had other ideas and continued their siege, wiping out 80,000 people in Damietta. Francis was sickened and disheartened and returned to Italy.
The sultan, forced to retreat, soon turned the tables on the Crusaders and had them surrounded and starving. But instead of going in for the kill, he sent his enemies food and feed for their animals. Many lives were saved and both sides returned home.
"The sultan had every reason in the world to let the Christians die, but he responded with mercy and compassion," Kronemer said. "It is not the reason the Crusades ended, but it really was the beginning of the end and it was these two men of faith who got that moving."
Why tell this 800-year-old story now? Kronemer believes many of the circumstances that made the mass slaughter of the Crusades possible are in play again between East and West, especially the dehumanizing of one's enemies and rhetoric that "otherizes" those who are considered different because of religion or race.
"When people begin otherizing that bleeds out into" other areas, such as politics, Kronemer said. "I think that is a period I think we are in right now. We are hoping that the film raises that and provides a model through these two individuals to how you can overcome that."
That's reflected in the viewing parties Kronemer's production company, Unity Productions Foundation, and PBS have organized nationwide for the airing Tuesday. There are more than 100 scheduled, ranging from family gatherings to interfaith meet-ups. Muslim, Christian, Jewish, Buddhist and Baha'i groups are hosting parties from Massachusetts to California.
Michael Lavach and his wife will hold a viewing party at their house near San Diego the next time their monthly devotional interfaith group gets together. They are Baha'is and saw the film a year ago at the invitation of a Catholic sister who knew of a screening.
"What we are trying to do in (their devotional group) is break down barriers and help people become more open to different faiths so they can understand that all major belief systems come from one God and should not be a cause for fighting," he said. "We thought if St. Francis and the sultan can come together, why not everybody else?"