Conclave: How realistic is the movie which lifts a lid on how a pope is elected?

This has been a blockbuster election year politically, so it's fitting that a new movie shines a light on an ancient and highly secretive voting process: the selection of a new pope .

" Conclave ," directed by Edward Berger ("All Quiet on the Western Front"), and featuring a stellar cast of Ralph Fiennes, Stanley Tucci, Isabella Rossellini and John Lithgow, brings to life the heady mix of mystery, ritual, tradition but most of all the politics of the papal selection process.

The highly anticipated movie , which already has an awards buzz around it , is based on the 2016 thriller by British novelist Robert Harris, which describes itself as a tale about the "power of God and the ambition of men," and imagines what the next conclave could be like.

Central to the storyline is the tension among the most senior figures in the Roman Catholic Church between the demands of their faith and the desire for high office. The film depicts the sotto-voce discussions in Vatican corridors and the subtle, behind-the-scenes politicking involved in a process where anyone seen to be campaigning for the position is likely to be ruled out.

But "Conclave" is already facing criticism from some within the church.

Bishop Robert Barron, the founder of the Word on Fire Catholic media ministry and one of the most followed Catholics in the world on social media, has told his followers on X to "run away from it as fast as you can." He described it as ticking "practically every woke box" and sending a message that the only way forward for the church is to embrace "the progressive buzz words of diversity, inclusion, indifference to doctrine."

He said the film unfairly portrays the church hierarchy as a "hotbed of ambition, corruption and desperate egotism, Conservatives are xenophobic extremists and the liberals are self-important schemers."

The movie tries to showcase the battle for the soul of the church that takes place during a papal election, highlighting tensions between progressives and traditionalists, the role (or lack thereof) of women and, in the case of Fiennes' character, Cardinal Lawrence, a crisis of faith.

For church-watchers, the big question for the next real-life conclave will be whether the cardinals choose a pope who continues in the more open mold of Pope Francis, or whether forces opposed to his papacy will be able to shift things in an alternative direction.

For the cardinals, the challenge will be finding a candidate who has a broad enough appeal and the personal credibility to be chosen for the role. While this is a political consideration, in Catholic theology the electors are supposed to be guided by the Holy Spirit.

Steven P. Millies, the director of the Bernardin Center at Catholic Theological Union, a theological college in Chicago, said the movie's depiction of the process is verified by reports from cardinals that conclaves are an exercise in "careful coalition-building" as they weigh up the church's future.

"A conclave is a political event in the best sense of politics — it is a thoughtful, even prayerful consideration of a community's future," he told CNN. "The 'politicking' does not deny the involvement of the Holy Spirit (it doesn't guarantee it either, of course). Whether the Spirit is heeded is up to the cardinals. But the Spirit is present, and the vote-counting is a necessary part of the process."

To avoid outside lobbying and ensure cardinals are free to pick who they think is the best man for the job, conclaves take place in strict confidentiality, with participants sequestered away from the world. They are forbidden from speaking to anyone outside of the process, which can take several days, including reading media reports or receiving messages.

Only cardinals below the age of 80 have a vote. They cast them in the Sistine Chapel, in front of the awe-inspiring sight of Michelangelo's "Last Judgment," writing their choices on paper ballots that are then burnt after being counted.

Rounds of voting continue until one candidate has a two-thirds supermajority. The crowd waiting outside is informed that a pope has been elected when the chimney above the Sistine Chapel billows out white smoke.

"Conclave" works hard to be as realistic as possible. Harris was helped with his novel by the late English cardinal Cormac Murphy O'Connor , who took part in the 2005 and 2013 conclaves, while the screenwriter, Peter Straughan, and the filmmakers were given a private tour of the Sistine Chapel.

The movie gets many details right. We see cardinals wheeling in their overnight bags as they start the process and scenes of them having a cigarette beforehand. It recreates the rooms in the guesthouse – the Domus Sanctae Marthae – where the cardinals stay during the conclave, with communal meals and buses ferrying them back and forth between voting sessions.

We are also shown the sealing of the deceased pope's room and destruction of his ring, the oaths sworn by the cardinals before voting, the use of chemicals to ensure that the correct color of smoke issues from the chimney to indicate the result (black for no decision and white to show a pope has been chosen), and the sweeping of the Sistine Chapel for listening devices.

There are, however, small things it gets wrong, such as details of how the tables are laid out in the Sistine Chapel and the way cardinals address each other. But the least believable part of the film is its unlikely ending, which we won't give away here.

Tom Reese, a Jesuit priest and church commentator based in Washington, DC, gave CNN this verdict: "(The) acting and production values were great, but the plot twists were bizarre and unbelievable."

For Millies, however, the film is not primarily about the final plot twist or even about the processes of choosing a pope. He sees it as a story of one cardinal grappling with his faith, and finding it again – something he describes as "beautiful to watch."