Isaiah Washington, left, is a standout in his portrayal of a seemingly macho father to Julian Walker’s Randy in “Blackbird.” (RLJ Entertainment)

Randy is a Southern choirboy who turns to a portrait of Jesus on his bedroom wall when times get tough. His friends make the distinction between a real sin and a “Randy sin,” because the teen — a virgin who doesn’t curse, drink or stir up trouble — sets such a high bar for appropriate behavior.

There’s just one thing. Randy has been having erotic dreams about one of his male classmates. And, despite his prayers, Jesus isn’t making them go away. That’s the tricky dilemma at the center of “Blackbird,” an adaptation of Larry Duplechan’s novel: Randy’s religion is at odds with his nature.

But that essential and important struggle is hardly the movie’s only conundrum — and that’s the melodrama’s biggest flaw. Anything that can go wrong, will — often in spectacular fashion. For starters, Randy (newcomer Julian Walker) is dealing with the separation of his parents, a split that arose from yet another dramatic episode. Six years earlier, Randy’s younger sister disappeared, and his mother hasn’t been the same since. She spends her afternoons handing out fliers and taping “missing” signs to the milk cartons at the grocery store.

Randy’s friends are also dealing with a lot. One contracts a sexually transmitted disease, another contends with an unplanned pregnancy. Two characters are also grappling with their sexual identities.

Regardless, the heart of the movie is in the right place. And although some of the acting from the younger stars comes across as amateurish, a few performances truly shine, especially those of Oscar winner Mo’Nique and Isaiah Washington, who play Randy’s mother and father. Mo’Nique, who has gotten press recently for claiming she has been blackballed by Hollywood, also produced the movie with her husband, Sidney Hicks. She proves her talent here, turning in a powerful performance as a heartbroken woman who has lost one child and emotionally abandoned the other.

But Washington is even stronger in his more understated role. He comes across as a macho guy, driving around in a pickup truck and perpetually chewing on a toothpick. But in one sweet moment, he vows to love his son no matter what. Randy’s father, not to mention all of Randy’s friends, know the boy is gay.

It’s such a quiet, simple moment in a movie full of more overwrought ones — including a spiritual “deliverance” — but it makes a lasting impression. “Blackbird” would have benefited from using that approach more, rather than saddling a compelling drama with so much extra baggage.

R. At Angelika Pop-Up at Union Market and ArcLight Bethesda. Contains strong language, sexual situations, frank discussions about sex and drug use, all involving teens. 99 minutes.