In its native country, Satyajit Ray's 1960 film provoked considerable controversy when it was interpreted as an attack on religion. It took an intervention from founding father Jawaharlal Nehru, who urged people to see Devi before judging it, to assure the film a wide, global audience. Viewers outside India could just as well take it as an attack on superstition, but Devi may seem to them more like a psychological horror film about the breakdown of a woman's sense of self. The woman, Daya (Sharmila Tagore), is the young bride of Uma (Soumitra Chatterjee), scion of a respectable Bengali family who seeks a western-influenced higher education in 19th century India. While he takes classes in Calcutta and imbibes high culture, Daya moves in with the in-laws: father Kalinkar (Chhabi Biswas), brother-in-law (Purnendu Mukherjee) and his wife (Karuna Banerjee) and little son (Arpan Chowdhury). The old man worships Kali, more as a mother figure than as the destroyer westerners will think of. He has a man singing devotional songs that have a strong sentimental "mammy" quality on the steps of the estate. Before long, he's had a vision showing him that Daya is an incarnation of Kali. He installs her on a pedestal, where she becomes the confused but ultimately passive object of neighborhood devotion. For what it's worth, she'd already become the idol of her nephew, creating jealousy in the boy's mother, who sees her husband as a loser compared to his younger brother, Daya's husband. To the boy, Daya may be a second, better mother, and all the men in the household arguably see her as a mother figure, even though she hasn't yet had a child herself.
The situation escalates when an old man from the countryside brings his sick grandson to Daya, hoping that Kali (or "Ma") will heal the boy, his only remaining relative. When the miracle happens, through no special effort of Daya's, the cult spreads as Ray shows us long lines of pilgrims trooping in to pay homage. When Uma hears of this, however, he's scandalized. Returning home, he's determined to take Daya away from what he sees as craziness. By now, however, a seed, not of belief, but of existential doubt has taken root in Daya's mind. She can't be sure that she's not Kali, and so fears leaving her place at the shrine. Back there, the crisis comes when Khoka, the nephew, falls sick. His mom wants a real doctor to treat the boy, but he hesitates in the presence of the supposed god. Finally, with Khoka pleading for his Auntie, she entrusts her son to Daya -- but the family soon learns that "Kali" has taken Khoka for good. While the father wonders what sins he's being punished for, the dead boy's mother rages against the "witch" who "killed" Khoka. Of course, Uma is only more determined to rescue Daya from this meltdown, but by now, at the end, she just wants to run away from everything and everyone.
There's an irony in the background that Ray certainly must have appreciated. While poor Uma identifies Britain and the west with progress, in sharp contrast to the the superstition that ensnares Daya, their story plays out during the Victorian era, a time when English women were placed on pedestals and idolized, in a different fashion, to the detriment of their autonomy and agency. The Indian story differs in detail and intensity, but a universal point can be made about the treatment of women. Not even progressive Uma, after all, considers educating Daya as an option; she's an idol to him as well, in a way. Daya is trapped in a role that leaves little room for individuality or self-definition in an extreme instance of the social construction (or destruction) of identity. Angry Hindus may have seen Devi as a direct attack on their faith, but the wider world of cinema could just as easily see it as a tragic commentary on an emotional neediness among men that consumes and destroys women everywhere. The specifics of religion are just details that Ray deploys through visuals and especially with sound to tell his particular tale.