You can’t fault “Billy Lynn’s Long Halftime Walk” for its ambition. A sweeping satire of the politics and entertainment value of violence, the commercialization of “heroes” and conservative Christian hypocrisy, it’s got it all — combat, blood, sex, morality and Thanksgiving Day football.

But this blend of old-fashioned American exceptionalism seen through the eyes of a young man questioning it is a dreadful miscalculation in tone and temperament.

The acting is uneven, half the snarky jokes don’t land and the half that do won’t play in Peoria. Ang Lee & Co. set out to slaughter sacred cows, and only manage to wound a few.

The title character is an Iraq War hero, brought home with the rest of his squad to be briefly feted, courted and celebrated the American Way — at halftime in Dallas on Thanksgiving Day.

Billy (Joe Alwyn) collected a Silver Star for racing out under fire to retrieve his wounded Sgt. (Vin Diesel) in the middle of a firefight. The Men of Bravo, his squad, are now, in mid-Bush Administration, part of the halftime show in one of the most-watched football games of the year. Maybe they can gin up a little support for an increasingly unpopular war. That’s the plan, anyway/.

During this long day, as they meet with an agent (Chris Tucker at half speed) trying to sell their story to Hollywood, with the super-rich/super patriot owner of the Dallas football team (Steve Martin), the famed scantily-clad Southern belle cheerleaders, Billy flashes back to the combat, to a meal with his Texas family where his “Save my brother from going back” sister (Kristen Stewart) tried to talk him out of going through with all this.

Billy is troubled for “being honored for the worst day” of his life. His comrades in arms are all, like him, in a bit of shock. The inane and often idiotic questions from the press, from their civilian handlers, from players in the locker room and others make Billy fantasize that they all have the guts to answer them so bluntly as to wake the whole country up to the moral quagmire they find themselves in.

Only surviving Sgt. (Garrett Hedlund, on-point and sharp) is testy enough to actually do this.

“We just built a school there. That’s why all the teenagers keep shooting at us!”

Lee (“Brokeback Mountain”), working from Ben Fountain’s novel, gets at the unseemly marriage of the military and the NFL — which the military pays for all its “To Honor America” patriotic displays. The cynicism drips off every character as the camera tracks through long takes, capturing the spectacle and organized chaos backstage of putting on a big halftime extravaganza.

Billy catches the eye of a fetching cheerleader (Makenzie Leigh) who first wants to know if he’s a Christian before she “honors” him for his service — by servicing him backstage.

The soldiers are treated like cattle by the stage manager, like unwelcome “amateurs” by the burly stage crew.

But get past the satire and sheer absurdity of it all and you’re left with archetypal characters indifferently played by a cast that seems as aware that they’re “types” as we are. Alwyn makes an indifferent leading man, Stewart trots out more hair-fiddling angst, Tucker can’t summon the energy to make his agent arresting and Martin oozes patronizing contempt for the lesser mortals that keep rich guys like him rich. His Texas drawl comes and goes.

The worst of the worst, of course, is Diesel, miscast as a Zen drill (and combat) sergeant, a muscle-packed philosopher with a “Buddhist Thought of the Day” calendar at his disposal — apparently.

“If a bullet’s gonna get you, it’s already been fired.”

His pre-combat ritual with his squad is the damned silliest spin on combat movie cliches since Spike Lee tried his inept hand at making a war movie. Sgt. “Shroom” tells each and every man in his outfit “I love you.”

It’s so offbeat it almost works, but Diesel can’t get a single line to fall off his tongue as if he’s not reading it off a cue card.

Random scenes — all the jocks in the locker room know guns a bit too well, and the awkward questions about “killing” — sting.

But “Billy Lynn’s Long Halftime Walk” plays more like a sermon than cinema, a sermon delivered by uninspired preachers. And everybody knows America gave up sermons and thinking about Big Questions on Sundays for football and mindless entertainment decades ago.

MPAA Rating: R for language throughout, some war violence, sexual content, and brief drug use

Cast: Joe Alwyn, Vin Diesel, Garret Hedlund, Kristen Stewart, Chris Tucker, Steve Martin, Tim Blake Nelson

Credits:Directed by Ang Lee, script by Jean-Christophe Castelli, based on the novel by Ben Fountain. A Sony release.

Running time: 1:50