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At first glance a movie from the Judd Apatow factory set in biblical days might seem an intriguing change from the norm. But in spite of the shift in time and locale, as well as a script and direction by old pro Harold Ramis (“Groundhog Day”), “Year One” is basically the same old thing Apatow and his cohorts have served up in modern dress in pictures like “Superbad”—a vulgar, raunchy buddy comedy teaming up a loudmouth braggart and a doormat milquetoast. It’s just that instead of NYC or LA, it’s set in Sodom. Cue the gay jokes to go along with the ones about tits, asses, penises, farts, poop and urine—you know, all the stuff that makes up most PG-13 comedies nowadays.

The buddies are Zed (Jack Black) and Oh (Michael Cera), members of a prehistoric tribe of hunter-gatherers. Zed’s a hunter, though a thoroughly inept one, and Oh a despised gatherer, and both are lovestruck, Zed for beautiful brunette Maya (June Diane Raphael), also courted by thuggish brute Marlak (Matthew J. Willig), and Oh for Zed’s coquettish blonde sister Eema (Juno Temple). When Zed violates tribal religious rules by eating from the tree of the knowledge of good and evil, he’s expelled from the community, and Oh tags along with him.

That begins a series of biblically-oriented adventures, in which the duo meet up with goofy Cain (David Cross), who kills his prissy brother Abel (Paul Rudd) repeatedly in what he terms an accident, and circumcision-crazy Abraham (Hank Azaria) just as he’s about to sacrifice his randy son Isaac (Christopher Mintz-Plasse). Ultimately they wind up in sin city Sodom, where they start out as slaves, move up to soldiers, and ultimately become palace favorites under such patrons as Princess Inanna (Olivia Wilde) and the pleasure-loving High Priest (Oliver Platt), though the chief general (Vinnie Jones) remains a problem. Their real purpose, though, isn’t the pursuit of pleasure, but the rescue of Maya and Eema, who are also Sodomite slaves. It’s derailed, though, when Zed once again violates religious protocol by invading Sodom’s sanctuary.

As might be obvious from this, “Year One” is less a sustained comedy than a succession of vaudeville routines in which the stars do their customary shtick, the contemporary coolspeak deliberately anachronistic when delivered in period garb against “ancient” backgrounds. (Hardly a new idea—see Mel Brooks’s “A History of the World, Part I” and Brian Helgeland’s “A Knight’s Tale.”) The humor is definitely lowbrow, the sort of thing college frat brothers might come up with for a campus show, though calling it sophomoric would be an insult to second-year students. Many of the gags don’t so much build as simply meander around and then peter out with a quizzical shrug. The degree of pleasure you get from it all will largely depend on how much you appreciate Black and Cera. The former is all bluster ands braggadocio, an act that can—and does—get tiresome awfully fast, but Cera’s mousy delivery of his sarcastic throwaway lines wears better, even though some of the gags he has to suffer through (one involving the hirsute High Priest, another about his need to relieve himself while chained in a dungeon) are pretty revolting.

The others tend to play to the rafters, with Platt vamping it up maniacally and Cross and Jones going equally far. But Mintz-Plasse, who became a pop icon as McLovin in “Superbad,” doesn’t work a similar spell as Isaac, and an almost unrecognizable Azaria is actually dull as father Abraham. Of the women, Raphael and Wilde provide nice eye candy but little more; Temple has more personality than either. Technically the picture has a deliberately cheesy look that dovetails with its impudently carefree attitude.

But ultimately the most notable thing about “Year One” may be its gleefully dismissive attitude toward religion, from the takeoff on the Garden of Eden at the start to the irreverent treatment of Abraham and Isaac (and of Hebrew aggression against non-believers) and the send-up of Sodom’s “Holy of Holies” (and the use of human sacrifice to placate the gods)—at the close. Throughout Zed portrays himself as special, a Chosen One, and there’s a really extraordinary—almost somber—moment when the rationalist Oh actually doubts the existence of God. It’s hard to imagine anybody being much offended by this, presented as it is amidst so much risque farce; “Year One” is simply too silly to be condemned as blasphemous or taken seriously as a religious critique. In the last analysis, though, the motif is what’s most interesting about a movie that’s otherwise not much more than another raunchy, adolescent boys-out-on-the-town farrago, even if the boys are dressed in animal skins and the town is Sodom.