Having tackled the Scientologists in his most recent film Going Clear, documentary maker Alex Gibney takes on a cult that is even more ardent, and with considerably more members – that of Apple. His unsparing portrait of Steve Jobs will prove extremely displeasing to devotees, but it’s a riveting and important corrective to the myths Jobs helped to propagate, and which in the four years since his death have proved as seductive as his machines – and a lot more durable.

Gibney’s film comes ahead of the forthcoming Jobs biopic, directed by Danny Boyle and written by Aaron Sorkin. That film is said to comprise of three acts, each set just before one of Jobs’s presentations, but Gibney sets about zeroing in on certain aspect of Jobs’s life to paint a compelling portrait of a modern-day Citizen Kane. Jobs, a die-hard Bob Dylan fan whom Gibney paints as a product of 60s counterculture, was set alight by early “blue box” hacking technology, which allowed users to make long distance phone calls without paying for them, a way Jobs could delightedly stick it to the Man.

Yet this man, whose belief in his own righteousness was unshakeable, also terminated Apple’s philanthropic programmes, presided over huge corporate tax evasion, paid Chinese workers making iPhones a pittance, and only stumped up maintenance for his first daughter after dragging his ex-girlfriend through the courts, claiming that she was promiscuous and he was infertile, until a DNA test proved otherwise. Finally, he agreed to pay $500 a month – he was worth $200m at the time.

The film also spends some time on the 2010 incident when a drunk engineer lost a next-generation iPhone 4 prototype in a San Francisco bar, and the man who found it sold it to Gizmodo, who splashed its secrets around the world. Jobs, just one year from death from pancreatic cancer, enacted a revenge that included the police battering down of the door of the journalist’s house. Gibney presents footage of an ailing Jobs justifying such Mafia-style vengeance on the grounds that not to do so would be a betrayal of Apple’s values.

But what were these values? Gibney traces Jobs’s love of the hippy set text Be Here Now and his journeys to India, before Jobs concluded that he was most fulfilled in the Japanese walled gardens of Zen Buddhism. Jobs took on Zen’s minimal design, and applied it to Apple with world-eating success, but the spiritual dimension was beyond him. Aged 18, Jobs had knocked on the door of Buddhist monk Kobun Chino Otogawa and said that he believed he was enlightened, but didn’t know what to do with it. The monk, who died in 2002, asked for proof, and Jobs returned with a chip from a PC, a first computer he would name Lisa, after the daughter he had fought so hard not to acknowledge. “He’s brilliant, but he’s too smart,” was the monk’s conclusion.

The film points out that Jobs’s genius was in personalising computers – Lisa being the first – but it also reveals that this impulse came from a pretty messed-up place. As well as being deeply ambivalent about being a father, Jobs also felt at once rejected and anointed by the fact that he was adopted. Jobs has somehow transmitted that mess to us too. Our iPhones connect us to faraway friends and family, yet we spend increasing amounts of time alone with them, seduced by machines that can never really fulfil us.

Gibney’s film concludes that Jobs had the monomaniacal focus of a monk but none of the empathy of one, and it makes a powerful case. Jobs’s was an astonishing life of such significance that it will probably be studied for centuries, and Gibney does not downplay his genius. Yet the kernel of the film is probably the ex-girlfriend who says that Job “blew it”. How so? Jobs achieved things that the vast majority of us would never dream of. Yet Gibney’s film forensically anatomises the contradictions, the ruthlessness, and the pointlessly crappy behaviour that reveal Apple’s ideals to be a sham, even while the products themselves continue to prove almost irresistible.