The acute and sometimes obtuse angles of Bob Dylan’s career have teased and infuriated his public for more than half a century. But nothing – not the bizarre Christmas album, his no-show at the Nobel ceremony or allowing his music to be used in a Victoria’s Secret lingerie ad – has provoked the degree of derision that greeted his conversion to Christianity at the end of the 1970s, which is the subject of a film to be shown on the BBC later this month.

Vainly anticipating the oneiric visions of Mr Tambourine Man and the dazzling surrealism of Desolation Row, his audiences felt betrayed when the seemingly conventional opening line of a new composition – Are you ready? – was followed by a fusillade of more uncomfortably precise demands expressing his newfound faith: “Are you ready for the judgement? Are you ready for the terrible swift sword? Are you ready for Armageddon? Are you ready for the day of the Lord?”

Many were not. Dylan’s Christianity was of the earnest, unyielding variety, and listeners who had responded to the sceptical injunctions of his early work – “Don’t follow leaders,” he had told them in Subterranean Homesick Blues – were repelled by his new allegiance to the Christian deity, even when some of the resulting songs, such as Slow Train Coming and Every Grain of Sand, turned out to be pretty good.

His friend Allen Ginsberg had a more positive view: “He seemed to be trying to transcend himself into something else, which I thought was healthy,” the poet said after attending one of the concerts. But, as so often in Dylan’s career, it turned out to be a passing phase, lasting from 1979 to 1981. “Jesus himself only preached for three years,” he told a reporter from the Los Angeles Times, possibly with his tongue in his cheek.

The recorded legacy of that brief period was largely overlooked until the release late last year of Trouble No More, a compilation of concert recordings from the born-again period, the 13th volume of his long-running Bootleg Series of previously unreleased material. Accompanying the £150, eight-CD deluxe edition of the recordings was a ninth disc containing a new hourlong film that casts a more benign light on Dylan’s adventures in evangelism.

Working with newly unearthed film of concerts in the spring of 1980, the director Jennifer Lebeau exploits the close-up footage to reveal not just the high quality of Dylan’s performances (“I think he was probably singing better than he’d sung in many years,” his guitarist Fred Tackett said) but the degree of his commitment to the message he was trying to put over. This had escaped the attention of stadium audiences in an era before the introduction of giant screens.

Lebeau was also asked by the Dylan camp to break up the concert footage with half a dozen two-minute sermons. Not the ones with which the singer had regaled his audiences almost 40 years ago but diatribes on designated themes – hypocrisy, virtue, temperance, gluttony, justice and prudence – commissioned from the writer and critic Luc Sante.

“My instructions from Bob included one to go easy on the fire and brimstone,” Sante – who, at 63, is 13 years younger than Dylan – said this week from his home in upstate New York.

Instead the writer, who was brought up as a Catholic but had not attended church in 50 years, found inspiration in the recordings of African American preachers of the 1920s. “Men like the Rev JM Gates, the Rev AW Nix and the Rev DC Rice were huge sellers in their day. They were southern preachers and their words brought comfort to a great many people who had moved north in the Great Migration and were perhaps feeling lonely and isolated.”

The sermons are delivered against the stained glass windows of an Episcopalian church on New York’s Upper East Side by the actor Michael Shannon, recently seen as a villainous US army colonel in The Shape of Water, the winner of the 2018 Oscar for best picture. In a variety of sharp three-piece suits, Shannon stays just this side of a caricature of the typical 1970s televangelist while biting down hard on Sante’s words: “Justice is not always served on this earth! Sometimes the wicked are rewarded and the virtuous are made to suffer. That may happen in this life, but it will not happen in the next…”

During the Q&A session following a screening of Trouble No More at the New York film festival, an audience member criticised the decision to explore this darker material rather than reflect the beatific spirit of the born-again movement into which Dylan had been drawn.

Shannon had an answer. “As beautiful a period as this was in Dylan’s career, he’s moved on,” the actor said. “There’s still a lot of pain and suffering in the world – that sunshiny vibe isn’t going to cut it. It’s a little more complicated than that.”

Of course it’s complicated. It’s Bob Dylan.

Trouble No More will be screened on BBC4 on 30 March.