The X-Files: I Want to Believe 

Full disclosure: I am an “X-Files” fan. I watched every one of the show’s 202 episodes, from the unheralded 1993 pilot to the limping 2002 finale — most on their original air dates. I own the first three seasons on DVD and the 1996 issue of Rolling Stone with David Duchovny and Gillian Anderson cuddling in bed on the cover. (Back then, the notion that the sparring, sexually repressed FBI paranormal investigators might ever get it on generated gigabytes of dial-up Internet discussion.)

So I’m sorry to report that this movie isn’t very good. When we do see Mulder and Scully between the sheets — not quite a spoiler, as their relationship was strongly implied by the end of the series — it’s about as sexy as watching your parents’ long-married friends in a post-coital moment. That’s not because the two stars are “old”; it’s because they’ve done this dance too many times before. They could sleepwalk through these roles, and director/co-writer Chris Carter doesn’t give them much else to do.

Though Carter created “The X-Files,” he was far from its best writer — that was Darin Morgan, who found ways to make paranoia postmodern and funny. Carter was the idea man, well-intentioned but heavy-handed, and one of his best ideas was to put the words “I Want to Believe” on a UFO poster in Special Agent Fox Mulder’s office. The words “want to” made all the difference. Though he was willing to give benefit of the doubt to pretty much anything, from shape-shifting aliens to bleeding stigmata to killer cockroaches, Mulder kept his options open: Like increasing numbers of Americans in the ’90s, he was a believer in search of a solid faith. His partner, by contrast, had two of them, science and Catholicism, which made her considerably more skeptical about zombies and werewolves.

Rather than try to resolve the show’s hopelessly snarled “mythology” — the alien invasion involving corn and bees that was supposed to happen by 2012, or maybe not — Carter has crafted a modest, self-contained story that returns to that central issue of belief. Scully has left the Bureau and is practicing medicine at a Catholic hospital, where she’s contacted by an agent (a wooden Amanda Peet), who wants her to enlist Mulder’s help in dealing with an informant. Father Crissman (Billy Connolly) may or may not be having psychic visions that could help save an abducted woman. Since he’s a defrocked priest and convicted pedophile, Scully wants nothing to do with him, while Mulder insists the truth may come from unlikely sources.

Lather, rinse, repeat. Part of the problem with this story is that it’s sloppily plotted, as if Carter and co-writer Frank Spotnitz had no idea how to stretch a 43-minute TV episode — which this essentially is — to feature length. They do their best to offer up everything fans could conceivably want: tense moments, gross-out thrills, philosophical arguments and tender moments between the two leads. In the process, they lose focus. Though a few scenes rise to the queasy intensity of vintage “X-Files” — when Anderson argues with Connolly, or the villain (Callum Keith Rennie, the scary Cylon from “Battlestar Galactica”) stalks a new victim — they don’t hang together, and the film builds to a laughable climax. If nothing else, it shows that a badge-less Mulder can’t do much crime fighting with just his sarcastic delivery.

More importantly, that sexual tension thing aside, the characters don’t seem to have, well, changed. Scully’s desire to renew her faith so she can help a young patient is touching. But when she asks Mulder not to make her “look into the darkness” anymore, her concern seems a bit belated: Given all they’ve seen and suffered — near-death experiences, bereavement, alien-induced cancer, alien-induced pregnancy, you name it — these two should be battling post-traumatic stress together, not having the same old arguments. With urgent new conspiracy theories swirling around us, you’d think “The X-Files” could thrive in the post-9/11 world. Instead, it’s become a period piece.