From “Saved!” to “The Miseducation of Cameron Post,” Sundance movies tend to paint fundamentalist Christians as severe, cult-like zealots, hellbent on brainwashing the next generation. While such portrayals can certainly be cathartic for those scarred by conservative upbringings, it’s a refreshing change to see this milieu treated with the level of nuance that Laurel Parmet brings to “The Starling Girl.”

Set in a small Kentucky town where morality is strictly enforced, Parmet’s promising, evenhanded debut focuses on a religious teen (“Little Women” star Eliza Scanlen) who’s never had reason to question her faith, until a crush on her handsome youth pastor (Lewis Pullman) awakens her sexuality and scandalizes the community. For the adults in this repressive rural enclave, organized religion seems to provide the discipline and structure they seek. But for 17-year-old Jem Starling, their values are starting feel like a straitjacket.

Jem dutifully honors her father (Jimmi Simpson) and mother (Wrenn Schmidt), but her parents are pressuring her to court a pimple-faced fellow parishioner named Ben (Austin Abrams) — seemingly the last person she’d want as a husband. But young women like Jem don’t get much of a say in the patriarchal Christian society in which they’re raised.

In an early scene, Ben’s mother approaches Jem after the dance performance she’s given in church and expresses her concern. Jem’s brassiere was visible through her blouse, she says, and such things pose an inappropriate distraction for the men during worship. Suddenly self-conscious, Jem appears to shrink into herself, like Eve in the Garden of Eden, discovering the shame of her own body. But this moment doubles as a reminder of Jem’s newfound power, which she puts to the test when Ben’s older brother Owen (Pullman) returns from a mission trip.

The script doesn’t explicitly state what Jem sees in Owen, though it’s not hard to guess: Long-haired and handsome, he’s a bit of a rebel, but also devout — traits he shares with Jem’s father, who was a member of a Christian rock band during his wilder days. Owen has just come back from Puerto Rico, which makes him relatively worldly in her eyes, a symbol of the possibilities beyond this “Handmaid’s Tale” community of homemade dresses and honor-thy-husband dynamics. Jem imagines the two of them running off together, and starts looking for ways to get his attention.

“The Starling Girl” is rigorously realistic, without fantasies or flashbacks, but on one point, there can be little doubt: After dance practice one afternoon, she deflates the tire on her bicycle so Owen will be obliged to give her a ride. It’s not long before they’re making out and more. Owen is married with a pregnant wife, but he finds Jem irresistible. Another director might have emphasized the erotic dimension of this forbidden attraction between a young churchgoer and her religious instructor, between a minor and her ostensibly more mature first love, à la “The Thorn Birds” or “Call Me by Your Name,” but Parmet strikes a more nuanced tone.

Seeking identification over judgment, the film invites audiences to observe how transgressive it feels to discover the very thing that young women are admonished to protect — their sexuality — can seem so intoxicatingly “right” when experienced for the first time. Jem is too naive to recognize all the ways in which her connection to Owen isn’t healthy or sustainable. But the affair breaks the spell of Jem’s upbringing, challenging the assumptions of her obedient childhood and liberating her from a kind of brainwashing.

Still, Parmet is generous enough to acknowledge that while not the right fit for Jem, this ultra-conservative system could be the right answer for others — adults who need that kind of discipline in their lives, perhaps. It’s the children who suffer. Consider the young man roughly Jem’s age who was sent away to King’s Valley, a disciplinary camp for those who stray from the church’s teachings — the same place where it’s suggested that Jem must go after her scandalous behavior is discovered. It’s either that or find a way to skip town and start over somewhere else. As it happens, that’s how nearly all small-town coming-of-age indie movies conclude: by getting out of Dodge. Life isn’t automatically better in the big city, but at least there’s potential.

Parmet finds a poetic way to portray Jem’s liberation, but more important is the lead-up: the bumpy process by which she comes to realize she wants more from life than the restrictive existence she’s known till now. Jem’s involvement in the church dance troupe shows what little creativity she’s allowed to express, which the adults around her, including Owen’s wife, Misty (Jessamine Burgum), carefully monitor and control. Whereas they reprimand her for showing individualism — or “pride,” in church-speak — audiences yearn to see this girl dance. Sure, Jem’s surname may be slightly on the nose, but in the end, there can be no doubt this young Starling needs to ditch her flock and fly the nest.