How Pope Francis became a movie star

German director Wim Wenders tells the BBC why the chance to make a documentary with Pope Francis was a heaven-sent opportunity.

Over the course of a 50-year career, Wim Wenders has worked with such international luminaries as Mel Gibson, Alicia Vikander and rock band U2.

Yet the German film-maker witnessed global recognition on a whole new level when he accepted an invitation from the Vatican to make a film about the Pope.

Combining interviews with the pontiff with footage of his travels, Pope Francis: A Man of His Word shows its subject commanding audiences far greater than any star could muster.

So did Wenders see any similarities with some of his other collaborators during the four afternoons he spent conversing with His Holiness?

"The Pope has the same presence as some of the greatest movie stars I've worked with," says the director of Paris, Texas, Wings of Desire and Buena Vista Social Club.

"But it comes from inside, from his convictions and his faith, and from his desire to talk to all of us.

"He doesn't have it because he's full of himself," continues the 72-year-old. "He's incredibly modest - a real, humble man.

"It's not an act; he's not an actor. He's interested in everybody he meets, and in true communication."

Wenders believes it was the Pope's desire to reach as wide an audience as possible that led him to make his big-screen debut.

It certainly wasn't because he was familiar with Wim's work. "I know for a fact the Pope doesn't know movies," he shrugs.

"The first thing he said to me was, 'I've heard good things about you, but I must confess I haven't seen a single one of your films.'"

The initial approach instead came from Dario Vigano, the film-loving head of the Vatican's communications department.

Monsignor Vigano has since resigned after facing criticism for doctoring a letter sent by Pope Francis's predecessor, Benedict XVI.

Wenders insists no subject was off the table and that the Pope "wouldn't have had it any other way".

During the documentary, which had its premiere at the Cannes Film Festival in May, the 81-year-old is seen addressing the sex abuse scandals that have rocked the Catholic Church in recent years.

"He talked about paedophilia without hesitation, and that was when he was at his angriest," says the director.

"We really felt the fury in him - that he would like to do so much more but he's only one man."

At other points in the film, Pope Francis expresses concerns for the environment and his more general hopes for a more equal world.

Central to his thinking are "the three Ts" - "Tierra, Trabajo y Techo", the Spanish words for land, work and housing.

"You don't expect the Pope to mention salaries, but he doesn't hesitate to be concrete," Wenders continues.

"It takes guts to say we're destroying our planet and we're all going to go down if we don't take care of our own house."

Spending time with the Pope clearly had an impact on the three-time Oscar nominee, who found himself questioning his own tendency towards acquisitiveness.

"I have a big addiction," Wenders confesses. "I buy a lot of music because I want to stay on top of things.

"I realised that a lot of this music I only listen to once. I keep buying more and it's ridiculous."

Given there are an estimated 1.2 billion Roman Catholics in the world, there is sure to be an audience for Wenders' film.

Yet the director hopes Pope Francis: A Man of His Word will do more than preach to the choir.

"The film is about a man who wants to move his church and talk to everybody, not just Catholics and Christians," he concludes.

"His is not just a Christian message. It's a message to all people of good will, and that's who he wants to address."

Pope Francis: A Man of His Word is out in the UK on 10 August.

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