This Christmas the sell-out Off-Broadway production of The Screwtape Letters, an adaptation of C.S. Lewis' famous satirical novel, will come to London to make its European debut. Actor Max McLean, who plays the titular character, Satan's top psychiatrist, spoke to Christian Today about faith, theatre, and bringing C.S. Lewis back home.

The Screwtape Letters was written by Lewis in 1942, as the correspondence of a senior demon – Screwtape – to his nephew Wormwood, advising him on how to damn the soul of a human subject on Earth. Lewis's work won wide acclaim and catapulted the humble Oxford don into international renown, selling millions of copies around the world.

Max McLean and Jeffrey Fiske first adapted Lewis's story into a theatre performance in 2006, which sold out in New York City and across the U.S. Now McLean is bringing the show to Park Theatre in London, premiering on December 8 and running until January 7, 2017.

The show presents a "gnarly inverted universe" narrated from the offices of Hell, where antihero Screwtape and his acrobatic admin Toadpipe communicate with "junior neophyte demon" Wormwood to plot the damnation of a human 'patient'. The play follows these two arcs: the world of Hell – the demonic domain of Satan, or "Our Father Below" – and Earth, where an unseen character named only as 'the Enemy' protects the patient from Screwtape's schemes. That's God, by the way.

"It's a predator/prey story," McLean told Christian Today. "Screwtape is a roaring lion, seeking whom he will devour. The prey is every one of us, if we're not vigilant."

The show follows the subversive style of the book, expressing theological wisdom through the voice of a demon. McLean performed a short excerpt from the show at a launch event, where Screwtape speaks of how he combatted a patient's pious train of thought by suggesting it was "time for lunch". In Screwtape's words:

"It's funny how these humans think of us as putting things into their minds; our best work is done by keeping things out."

McLean is a Christian, and his faith is central not only to what he does, but how he does it. "I don't even think I would have attempted it without personal faith," McLean told Christian Today. "Part of it was my admiration for C.S. Lewis. He wrote this as a kind of confessional. He is the patient of the story. In many ways when he's expressing how Screwtape is challenging him, it's also how he challenges me."

Is it a struggle for a Christian to be constantly playing a role centred on the 'dark side'?

"At the beginning I really enjoyed the character... the whole theatrical experience of it was really entertaining," McLean says. "But I did come to a place where the cynicism of Screwtape was beginning to become a bit weary[ing]."

That said, McLean clearly enjoys the performance: he may be a demon but he inhabits the role with the charisma and delight of a stage-magician-come-Oxford-professor. He has certainly made it his own, but the role was actually originally suggested to him by co-adaptor Jeffrey Fiske, who "suggested that I'd make a really good Screwtape. I didn't know if that was a compliment or not."

The show's insight into the psychological manipulations of Screwtape provide an "extraordinary imaginative tool... if it came straight at you you'd turn it off immediately." Its alternative perspective engages the imagination, and prompts the audience to ask, "Who are we? An eavesdropper, a voyeur? The patient?" McLean says. "People are being spoken to in a way that they're not really aware of. "

McLean often follows up his performances with a Q&A session with the audience, where he finds nearly everyone stays to engage in conversation. Do non-Christians sometimes respond to this theological work with suspicision? "I don't think people are particularly against the tenets of the Christian faith, but sometimes feel it comes on a bit heavy," McLean says. "They need time to process it."

That said, although this is based on a deeply Christian adaption which has reached a vast non-Christian audience, McLean's theatre is not church ministry. "We don't do altar calls," he says. Yet the event is a great platform for engaging those otherwise disinterested in Christianity or religion. "What normally happens is they come with friends, and the invitation sparks a conversation."

Christianity can have a bad reputation in the arts. Some Christians don't particularly care for creative expression, while 'faith movies' in the public sphere are often criticised for being heavy-handed, aggressively preachy, or simply a bit rubbish. I ask McLean how he sees the situation as a Christian artist who has won wide acclaim outside the church. "There's a lot of bad art both Christian and secular," he says, and he agrees that often there's "not much grace on people trying to integrate their faith and their art. They have to fail."

He says there's a pressure on some Christian artists to be more overt, but those who do need to be wary of the "tune-out factor" from audiences who'll disengage with what they feel they've already heard before. For McLean, Lewis is the model: "Lewis was overt, but he was so good at it, it was always interesting, entertaining, surprising."

At the press event McLean is asked if secular London is ready for Lewis' Christian message. It's a fair question – Park Theatre isn't religiously affiliated – but McLean seems confident: "Is the Christian message of Screwtape going to go down well over Christmas? I hope so!" If anything he's afraid of Christians: the "embarrassing supporter" who tries to help McLean along but only ends up turning other members of the audience off. McLean insists he isn't there to preach or to win an argument: "I'm not trying to score points here. I really want to engage in dialogue."

Next year will mark 75 years since Lewis wrote The Screwtape Letters, so what's the secret to its endurance? McLean puts it down to the genius of Lewis, and his "unusual constellation of ideas in a morally inverted universe... Lewis himself said: 'People enjoy thinking, because they don't do it very much.'"

Well if you like thinking, or laughing, or both, then this show looks promising. McLean plays Screwtape with class, wit and a worryingly charming presence. He's no moustache-twirling villain; he's as subtle and entertaining as any convincing demonic anti-hero should be.

As for what his greatest joy on the stage is, McLean's answer is simple: "Capturing people's imagination. When the lightbulbs turn on, it's very exciting."

The Screwtape Letters comes to the Park Theatre, London on December 8 and runs until the January 7, 2017. For more information, click here.