“My mama, she believes in the Pentecost,” Jack Twist (Jake Gyllenhall) remarks to Ennis Del Mar (Heath Ledger) one cold day on Brokeback Mountain, where the two poor ranch hands have taken a job watching sheep.

Jack seems to be confusing Pentecost and the Apocalypse, though: “I guess it’s when the world ends … and folks like you’n me march off to hell.”

“Speak f’y’self,” returns Ennis. “You may be a sinner … but I haven’t had the opportunity.”

That’s about to change. One cold night, Jack and Ennis wind up sharing the tent. Then, much to Ennis’ shock, Jack unceremoniously offers him the opportunity to sin — and he takes it.

Thus begins Ang Lee’s Brokeback Mountain, widely known as “the gay cowboy movie” and a potential front-runner for this year’s Best Picture Oscar.

Much later, Ennis happens to meet Jack’s parents, who apparently have some idea of the sort of relationship their son had with Ennis. Mr. Twist seems to take a dim view of the whole business and of his son in general, but Mrs. Twist seems more sympathetic and understanding, even letting him take a memento from the room Jack grew up in.

Does this scene suggest that Mrs. Twist, as a true Christian, has accepted her son without judgment, and likewise accepts this stranger and his relationship with her son in the same way? Does she love the sinner and hate the sin, or is she not particularly bothered by either?

Such ambiguity is a mark of the distance between Brokeback Mountain and a film like Peter Mullan’s The Magdalene Sisters, in which all the characters come neatly labeled as victim, hypocrite, accomplice or abuser. The Magdalene Sisters is a work of uncomplicated agitprop; Brokeback Mountain is a work of art, more concerned with telling a story about characters than with making sure that the viewer feels a certain way about a moral issue.

That’s not to say that Brokeback Mountain doesn’t have a point of view. It does — a profoundly problematic one, one that makes it potentially far more insidious than mere propaganda.

Ennis and Jack each marry but continue to carry on together, and their ongoing affair is allowed to be at least as morally problematic as any other extramarital affair. A lesser filmmaker might have painted the women as nags or harpies, but Lee allows Ennis’s wife Alma (Michelle Williams) a great deal of poignancy, and doesn’t avoid showing the pain that Ennis’s betrayal causes her as well as the children. Jack’s wife Lureen (Anne Hathaway), a rodeo princess and heavy-equipment heiress, is likewise appealing and sympathetic.

In time, Jack becomes increasingly jealous and resentful over the scarcity of their time together. He finds outlets for his restless appetites where he can, in turn provoking Ennis to jealous rage. Of course, all this pain is ultimately rooted in the furtive, surreptitious nature of their relationship, which in turn is largely grounded in the social realities of their place and time.

Jack harbors a secret wish for a different life with the two of them together on a ranch somewhere, but Ennis is haunted by an incident of murderous gay-bashing from his childhood, and the mutilated bodies his father made sure he and his brother saw.

Toward the end of the film is a similar act of violence, though here Lee’s directorial touch is at its most delicate. Where a heavy-handed director trying to drive home a message would have rubbed our noses in the violence, letting us hear the hate-filled epithets, Lee is content to suggest.

Unfortunately, there is one relatively minor but crucial respect in which Lee’s subtlety and even-handedness largely fail him. Whenever it considers straight men, Brokeback Mountain begins to verge toward Magdalene Sisters-style prejudicial stereotyping. Essentially every straight male character in the film is not only unsympathetic, but unsympathetic precisely in his embodiment of masculinity.

At its most extreme, the film’s brief against masculinity rests on its two incidents of deadly homophobic violence. Closely related is the pedagogy of Ennis’ father, with his horrific attempt to instill manly attitudes in his son by exposing him to the sight of the victims.

Also charged are Jack’s overbearing father-in-law and vaguely disapproving father; the sheep magnate of Brokeback, whose disdain for Jack is meant to be partly professional and partly homophobic; and even a random pickup-truck driver whom a volatile Ennis shockingly attacks and beats in response to the former angrily calling him an obscene name.

Other than a passing comment from Ennis about the “fire-and-brimstone crowd,” religion is almost totally absent. On the one hand, this means that homophobic attitudes aren’t particularly attributed to Christian teaching or belief. On the other, it means that the range of moral issues relating to Jack and Ennis’ relationship is rhetorically limited to conflicting commitments to their spouses and children — and, of course, the intolerance of society itself.

The film does not argue, but assumes, that the pain suffered by men like Jack and Ennis and those around them is the result of what is and isn’t permitted by entrenched social attitudes of intolerance and hate, which constrain such men from following their bliss. Compared to this film, the euthanasia advocacy of Million Dollar Baby, the anti-Catholicism of The Magdalene Sisters and the abortion activism of The Cider House Rules are practically child’s play.

Brokeback Mountain is nothing less than an indictment not just of heterosexism but also of masculinity itself, and thereby of human nature. It’s a jaundiced portrait of maleness in crisis — not only the maleness of the two central characters but also that of every other male character in the film. It may be the most profoundly anti-western western ever made: at once post-modern and post-heroic, post-Christian and post-human.

In the coming months, the news and entertainment industries will fete and lionize this latest push of the proverbial envelope. Glittering artifacts of the culture of death, the celebrations should not surprise us. Appall, yes. Shock, no. We’re beyond that now.

Content advisory: A strong but restrained, brief homoerotic encounter (no nudity); pervasive homoerotic themes; a couple of heterosexual bedroom scenes with brief female nudity; some nonsexual nudity; much objectionable language including profanity and obscenity; brief violent and disturbing images seen in flashback; a gruesome account of a murder-mutilation.

Steven D. Greydanus is

editor and chief critic of DecentFilms.com.