rated PG-13

After almost a decade of conservative Christianity dominating America’s social and political landscape, it feels like the never-ending debate between science and religion is finally entering a cooling-off period. But just like its protagonist, Harvard symbology professor Robert Langdon, “Angels & Demons” rushes in just as the party is wrapping up, ready to breathlessly opine on the tenacity of faith and the power of science. Except, of course, “Angels & Demons” is a summer thriller, and so these central ideas that ignite the plot have about the same weight as a crossword puzzle where all the across clues are about the pope and all the down clues are about particle physics. After that, all that’s left is for “Angels & Demons” to be thrilling, which it accomplishes just well enough to be entertaining.

Returning to solve this not-so-taxing puzzle is Langdon (Tom Hanks), the Harvard professor who unraveled Catholicism’s secrets in “The Da Vinci Code,” also based on the book by Seacoast author Dan Brown. This time around, the pope is dead, four of the church’s top cardinals are missing and a bomb (containing anti-matter harvested from the Large Hadron Collider) is set to destroy Vatican City. Claiming credit for this ecclesiastical calamity is the Illuminati, an ancient, underground conspiracy of scientists (Gallileo was a member) that has returned to destroy the church in its darkest hour.

Luckily for the church and Langdon (and, for that matter, the audience), the Illuminati likes to communicate in symbols and puzzles. With the blessing of the Camerlengo (Ewan McGregor), the departed pope’s right-hand man with ambitions of his own, it’s off to the library for Langdon, who must find the cardinals, locate the bomb and save the church. Of course, it all must be done in utter secrecy—the College of Cardinals is trying to elect a new pope, and St. Peter’s square is teeming with the faithful.

Like a lot of professors, Langdon is only likable when he’s in his academic element; otherwise, he’s either a pompous jerk or an ineffective action hero. When finally granted access to the Vatican archives, Langdon’s eyes light up and he gets all swoony. Glimmers of Hanks’ talent shine through and that arrogant edge drops away, replaced with a likable earnestness, which unfortunately vanishes all too quickly.

Otherwise, there’s nothing about Langdon for Hanks to really latch onto, a problem that plagues the other professors, priests and policemen scampering across Vatican City. They’re ciphers with less depth and complexity than the puzzles Langdon must decode. Apart from the Camerlengo, no one has even a hint of back story, and so Commander Richter (Stellan Skarsgard) is reduced to a grumbling heavy and Vittoria Vetra (Ayelet Zurer), Langdon’s sidekick and occasional physicist, wanders about Rome without any real reason for being there.

Outside the library, Langdon delivers long-winded lectures, usually given while running with Vittoria to the next crime scene. Most heroes are known for showing up in the nick of time, but Langdon always gets there a few minutes too late, and instead of saving the intended victim, he inadvertently makes the death a little more painful. Let’s just say that if you’re chained up and suspended over a raging fire and a Harvard symbologist offers to save you, things might work out better if you politely decline.

The murders themselves are suitably gimmicky and gory, just lurid enough to prove the stakes really are high amidst all of Langdon’s spiels. Although there’s a bomb about to explode and a quartet of cardinals slated for execution, “Angels & Demons” fails to maintain a sense of urgency. Director Ron Howard does what he can to balance the rather sloppy intellectual games and action scenes, but neither are strong enough on their own to work together. Car chases are slowed down by congested city streets, and the bits about the Large Hadron Collider creating anti-matter are just as scientifically dubious as the “red matter” in this summer’s “Star Trek.”

Whether intended or not, one of the things “Angels & Demons” does well is make Catholicism sexy. The usual science versus religion conflict is set up early on, but Howard’s sweeping shots of Vatican City and somber scenes of pomp-and-circumstance-filled Catholic ceremonies make it clear which side of the debate the movie falls on. Catholicism is so cool that even its enemy—an ancient cabal of scientists and philosophers—is awesome and intriguing. You don’t see any all-powerful conspiracies targeting the Southern Baptist Convention, do you?

Mostly, “Angels & Demons” is shockingly good at being average. Hanks, McGregor and the rest of the cast all give perfectly competent performances (it even seems as though McGregor is trying to dial his performance down at points, so as not to stand out too much), and the pacing is brisk enough that the ludicrous plot remains nothing but a blur. For all the theological posturing and weakly constructed debates about science and faith, “Angels & Demons” is about as empty-headed as the Bernini statutes that guide Langdon through Rome. The statues, at least, are worth some extended consideration; “Angels & Demons” merely merits a passing glance.