Amy Berg’s documentary “Deliver Us From Evil” has powerful and horrifying material to work with: a Catholic priest, the Irish-born Fr. Oliver O’Grady, who admits–right on film–that he molested at least 25 children during his 20-odd years in parishes during the 1970s and 1980s in the Stockton diocese in rural California. The bishops of Stockton, who included Roger Mahony, now archbishop of Los Angeles, instead of yanking “Father Ollie” from his pulpit and calling the police, either ignored complaints about him or ordered “counseling” and transferred him from parish to parish, always one step ahead of the outrage of his victims and their parents.

Eventually, in 1993, O’Grady was convicted of molesting two boys in his last parish, in San Andreas, Calif., sent to prison, and finally defrocked. He served seven years of a 14-year sentence and was deported to Ireland, where he now roams apparently free of police supervision and in close proximity to (at least in the film images) lots more children.

O’Grady himself, who spoke freely with Berg’s interviewers until he thought the better of it and stopped cooperating, is surely one of the ickiest true-life personages ever to appear on film. His now-white hair slicked back, his eyes batting flirtatiously, he flashes an ingratiating smile as he admits with a “Yeah!” that he feels aroused by children in their underwear. Unlike most child molesters, whose tastes run exclusively to one sex or the other, O’Grady was an equal-opportunity predator. With aplomb, he describes kissing on the lips and probing inside the underwear of little Nancy Sloan, whom he invited to spend the night with him (he describes these gestures as “showing affection”)–and with equal aplomb he describes working himself up to orgasm by fondling the genitals of an 11-year-old boy.

One set of parents, Bob and Maria Jyono, who regularly welcomed O’Grady as a house-guest, say that he raped their daughter, Ann, when she was five years old. Another now-grown victim, “Adam,” says that O’Grady wormed his way into his mother’s graces by having an affair with her so that he could freely sodomize Adam. A third of his alleged victims was a 9-month-old baby. As for remorse for his sins, O’Grady displays none, although he occasionally admits that what he did was “not correct.”

Meanwhile, back at diocesan headquarters, everyone, and (apparently) especially Mahony, seemed to be in thrall to the popular 1970s notion that psychotherapy had replaced old-fashioned notions of crime and punishment, and that talking to a “counselor” could actually cure people of pedophilia. They also seemed to believe that the best way to deal with a predator-priest was to keep mum–maybe no one would find out. Some of the most fascinating footage in Berg’s film is that of Mahony writhing and squirming while a lawyer in a civil suit (the San Andreas victim’s family won a $30 million judgment against the diocese of Stockton) reads aloud a smarmy letter from O’Grady to his bishop thanking him profusely for his latest parish transfer. Other footage of the embittered victims, now adults whose lives have been ruined, is intensely affecting, and interviews with the Jyonos, now frail, weeping oldsters who have lost everything, including their faith in God, are almost unbearable to watch.

Had Berg stuck to this quadrangle of O’Grady, Mahony, the victims, and their parents, she would have had a riveting film. Instead, she decides to turn it all into a generalized anti-Catholic screed. Talking heads appear and reappear, mostly disaffected Catholic priests and victims’ lawyers, who blame priestly celibacy for the O’Grady and numerous other sex-scandals that have recently torn apart the church.

I would have thought that lack of celibacy was the problem, but the idea is that if only priests could marry, they would leave minors alone. My first thought was: So what was Mark Foley’s excuse? If only congressmen could marry…. Another culprit cited in the film is the Catholic doctrine of the Eucharist, the teaching that the bread and wine at Mass become Jesus’s body and blood. How’s that again? Somehow there’s supposed to be a connection, one of the talking heads explains, between denying holy communion to a politician who supports abortion and molesting a youngster.

Admittedly, one of the disaffected, Fr. Tom Doyle, is a once-orthodox Vatican priest whose faith, like that of the victims and their parents, tragically went haywire after he tried unsuccessfully to persuade the bishops during the 1980s to do something substantive about priestly abuse, but in this movie, Doyle comes off like a superannuated ranter at a Call to Action conference: “The church is a monarchial, hierarchical, prosecutorial system!” he shouts. The movie also attempts to finger then-Cardinal Josef Ratzinger (now Pope Benedict XVI) as responsible for the sexual transgressions and states–falsely–that President Bush granted the pope “amnesty” in a victim’s civil suit. (Actually, a court ruled that there was no jurisdiction over the distant pontiff).

According to news reports, a spokesman for Mahony has complained that Berg’s film similarly misrepresents the facts concerning O’Grady transfer to San Andreas in 1984, implying that Mahony’s office lied to police who were investigating O’Grady at the time, whereas in fact the cops closed their investigation because the alleged victim’s family declined to prosecute. I don’t know whether this is true, but it is certainly true that Berg allows no quarter in her film to anyone who does not believe that the entire Catholic Church has been collectively guilty “since the fourth century” (as one disaffected theologian puts it) of permitting hundreds of thousands, perhaps millions of children to be molested by clerics with impunity.

Worst of all, when O’Grady is not onscreen with his mesmerizing, Hannibal Lecter-like projection of pure depravity, “Deliver Us From Evil” fails to deliver its viewers from boredom. The movie is at least a half-hour, perhaps an hour, too long, which means that Doyle, for example, gets to deliver his “monarchial, hierarchical” speech at least twice. We also must endure a tedious trip by some of the victims to Rome (watching people sitting on a plane–that’s fun!) plus a Ciao Italia! travelogue of the Eternal City while they ride around on a bus, visit churches, and try unsuccessfully to hand-deliver a letter of protest to the pope. Even the most determined post-Christian, Catholicism-hating, militant secularists may, I fear, discover that “Deliver Us From Evil” is no “Farenheit 911.”

That’s too bad, because “Deliver Us From Evil” contains one not-to-be-missed episode: When O’Grady gets back into the smarmy letter-writing game and make amends to his victims by sending each an individually penned letter inviting him or her to come to Ireland for a face-to-face meeting with him. The victims’ response when they get the letters: Blechhh! My sentiments exactly.