THE most sinister aspect of Jehovah’s Witnesses, as they are portrayed in “Apostasy”, is the way their apocalyptic and authoritarian beliefs are disguised by the bland aesthetics of a corporate away day. Meetings in their drab white-and-beige “Kingdom Hall” might as well be marketing conferences in a chain hotel. The group’s Elders are pasty middle-aged men in suits; they are so offhand about the world’s sinners being obliterated that they could be talking about an end-of-year bonus. They refer to “the new system” and “reinstatement” and “disfellowshipping” as if there were some logic to their jargon. And yet, “disfellowshipping”, as dull as it sounds, means being cut off so completely from the religion that your closest relations in it are forbidden to socialise with you. Could this be what happens to the film’s heroines?

A former member of “God’s organisation” himself, Daniel Kokotajlo has written and directed a sober yet revelatory drama which covers about a year in the life of three women in an unnamed northern suburb (it appears to take place in a particularly dreary part of Manchester, so you can see why the local Witnesses might be keen for Jesus to wipe it off the face of the earth). The women are 18-year-old Alex (Molly Wright), her big sister Luisa (Sacha Parkinson), and their determinedly devout mother Ivanna (Siobhan Finneran). The younger women’s father is neither seen nor discussed, a factor which is typical of Mr Kokotajlo’s understatement, but the viewer has to assume that he left or was kicked out of the organisation.

There are hints that Luisa may be next. Having made new friends in college, she is no longer quite so confident that “the great tribulation” is just around the corner. Alex, meanwhile, seems happy to be in the group, even though her anaemia may require her to have a life-saving blood transfusion, a procedure which the organisation forbids. She reassures herself, chillingly, by leafing through a book about children who have chosen to die rather than to defy this stricture—not that they would have had any informed choice in the matter—but the question bubbling beneath the narrative’s surface is whether she and her family will ultimately make the same choice.

Anyone who isn’t a Jehovah’s Witness may well be appalled not just by the brainwashing and all-round cultishness on display, but by the matter-of-fact callousness: doubters can be expelled from the group with less ceremony than if they were being downsized from an office internship. On the other hand, anyone who is a Jehovah’s Witness may well conclude that the film portrays the organisation fairly, and even positively. Mr Kokotajlo keeps speeches about its cruelty and anti-scientific dogma to a minimum, preferring to present the Witnesses’ practices with a quiet clarity and specificity. The film’s main Elders are obviously convinced that they are being kind and compassionate. But “Apostasy” keeps prodding at the organisation’s flaws, with the courage and determination that come with an insider’s knowledge, until the whole edifice comes crashing to the ground. Certainly, Mr Kokotajlo’s drama should make you look anew at those polite, smartly dressed people who stand next to racks of booklets in shopping centres.

In contrast with the recent films about Scientology, the pared-down, austere “Apostasy” doesn’t have the action-movie pace or skulduggery to attract a wide audience. Nor does it have, for that matter, the glamour of Scientology’s most famous adherent, Tom Cruise—not that any film with the title “Apostasy” was ever going to rival “Mission: Impossible - Fallout” at the box office. But it isn’t a cold factual exercise, either. Ms Finneran, a British television veteran probably best known for her roles in “Benidorm” and “Cold Feet”, is heartbreaking as the family’s tragic matriarch. Ivanna is utterly obedient to the organisation, but you can see the fear in her dark eyes and her tightly set face that her sacrifices may all have been for nothing.

Ms Finneran also knows how to deliver science-fiction-style dialogue with a desperate conviction which is both sad and funny. After one disagreement with her daughters, Ivanna promises them that “in a few hundred years, we’ll have forgotten about all this”. And when Luisa’s lecture timetable clashes with her commitments to the group, her mother asks, “How do you think Jesus will feel when he comes back at Armageddon to destroy the world, and he finds that you’ve been missing meetings so you can go to college?” Most of the film’s characters would deem that a perfectly reasonable question.

“Apostasy” is showing in Britain from July 27th