A wacky piece of pseudo-religious twaddle dressed up as a solemn, silly post-apocalyptic action flick, “The Book of Eli” is a tome that should have been kept resolutely closed. One can only assume that it was Denzel Washington’s faith that led him to get involved in such a goofy project, but if so it was definitely misplaced.

Washington plays Eli, a lone traveler through a devastated “Road”-like landscape (the cinematography by Don Burgess is technically in color, but it’s drained of everything but the grays, of course). We’re told that the earth suffered some sort of catastrophe three decades earlier, and the few survivors have descended to a brutal state of Hobbesian hostility. Eli is walking west, intending it seems, like the father and son in Cormac McCarthy’s story, to reach the sea—in his case, it will turn out, at San Francisco. (If he’s been trudging for thirty years, you can only wonder where he started. There must have been lots of detours even if it was the other end of the continent.)

Eli’s a dour, taciturn, generally peaceable fellow who immediately proves himself a sort of American samurai with a hefty blade when he dispatches a gang of marauders that accost him in the desert and demand his backpack. The pack is precious, since it contains a rare book—the King James Bible, all copies of which, we’re also told, were systematically destroyed after the cataclysm because some blamed it for the disaster. (How is never explained. Was it a war? A heavenly catastrophe? It couldn’t have been the Rapture, since Eli would certainly have been scooped up among the chosen.)

Anyway, that book is precisely what Carnegie (Gary Oldman), the dictator in the grubby town Eli wanders into, has been sending out his gangs of illiterate hooligans to find. Like some misguided modern version of Simon Magus, he believes that quoting the words of the Bible will give him a special power to control the unwashed masses and not only cement his control in the town but enable him to extend it over a wider swath of territory. So he tries to recruit Eli to his “government,” and when that fails sets off with his henchmen to catch up with the hero, who mysteriously escapes confinement, and secure the book.

But this time Eli’s not alone. He’s reluctantly allowed Solora (Mila Kunis), the daughter of Claudia (Jennifer Beals), Carnegie’s blind companion, to tag along with him. And they’ve wound up at the isolated house of a gaga old couple, George and Martha (Michael Gambon and Frances de la Tour), who’ve maintained a bedraggled civility while systematically wiping out interlopers (and apparently feeding on them). It’s there that Carnegie and his crew catch up with Eli and Solara, setting off a battle for the book that leads to ever more ridiculous plot turns: a bullet wound that can apparently be treated, at least temporarily, with little more than duct tape; a twist regarding the book that brings Carnegie the comeuppance he so richly deserves—even if it requires one to swallow a revelation about Eli that makes no sense in the context of all that’s preceded (for a clue, see “Zatoichi”—a much better picture); and a ludicrous epilogue pilfered from Ray Bradbury.

“The Book of Eli” is one of those amazing cinematic disasters that come along once in a while as evidence of just how far the ego of stars and filmmakers can go. (“Waterworld” and “Battlefield Earth” spring to mind.) As the first feature Albert and Allen Hughes have undertaken in years, it must have meant something special to them, and they treat it with the ponderousness one would expect of a project they considered “significant” (even the “samurai” bits and the “man-with-no-name” Sergio Leone moments lack any sense of fun), but one can hardly understand why. If it was the Christian element, why would they have been content with a throwaway line to the effect that “the book” had been used many times in the past to impose rule over the credulous? And if their picture is meant to appeal to a Christian audience, especially the fundamentalist sort that made Mel Gibson so rich, what’s to be thought of the final image in a reconstituted library, where the King James Bible is plopped onto a shelf beside a copy of the Koran? The suggestion that they’re equivalent may just be the sort of obligatory cop-out you’d expect in a Hollywood epic, but it can’t possibly suit the views of that target group.

As for Washington, one can imagine that so charismatic a star might jump at the chance to play this kind of post-apocalypse prophet (or maybe he was just envious of Will Smith’s “I Am Legend” turn), but his performance is, despite the occasional bursts of action, largely impassive and quite dull. Oldman just does his lip-smacking shtick—tiresomely repetitive—and no one else distinguishes him-or-herself, though Gambon and de la Tour have a bit of fun with the dotty old folk (whose names may refer to the first president and his wife, or to the couple from Albee’s “Virginia Woolf”—in either case quite pointlessly). An unbilled Malcolm McDowell shows up at the close, toning things down from his Rob Zombie “Halloween” turns but hardly at his best.

One aspect of “The Book of Eli” is certainly successful—the grubby post-apocalyptic look (Gae Buckley was production designer and Chris Burian-Mohr the art director, with visual effects supervised by Jon Farhat). But we’ve seen this before, most recently in “The Road,” and it’s no more enticing this time around.

Keeping with the religious motif, one might say that this movie is no Rapture; it’s more like the Tribulation.