Sometimes an actor is not acting. Take, for example, Mel Gibson’s recent public behavior and a good many of his films. The performance comes across as seamless mainly because he was never performing. We just happen to be watching someone acting naturally.

There is no particular theatrical style at work. What we see on screen is not a fictional portrayal but a self-portrait. In the case of Mr. Gibson, we can now finally conclude that Mad Max was never Max. He was always Mel. There was never any method to his madness.

On Friday, Mr. Gibson was arrested near his Malibu home for driving recklessly and drinking immodestly. He might as well have been charged with speaking like a lunatic, too. Apparently, while resisting arrest, he unleashed a barrage of unprintable expletives and vile anti-Semitism. His blood alcohol was notably high; his hatred of Jews even higher. Laced within the cursing and the contempt, he purportedly said, “The Jews are responsible for all the wars in the world.”

He has since apologized for having made “despicable” yet unspecified remarks that he now disavows and presumably doesn’t even believe. Yet he is quick to blame alcohol for his troubles when in fact whatever he was drinking might as well have been truth serum. Alcoholism was the aperitif to his anti-Semitism.

Mr. Gibson’s most successful screen personas have always depicted out of control individuals, the certifiably insane who we, improbably, still end up rooting for. In the moral universe of cinema, a righteous cause excuses lunacy. And audiences are reminded that the madness of Mr. Gibson’s heroes is not of their own making. In “Lethal Weapon,” Martin Riggs was most certainly lethal, but the trauma of Vietnam made him so. In “The Patriot” there was a butchered son; in “Braveheart” a murdered wife. And when it came to performing Shakespeare, Gibson inhabited Hamlet, the Danish prince who retreated from his right mind all because of his uncle’s treachery and his mother’s adultery.

Speaking of families, Gibson’s anti-Semitism may have actually originated with his father. Remember it was Hutton Gibson who, most infamously, denied the existence of the Holocaust, calling it a “fiction” and asserting that there were more Jews living in Europe after World War II than before. (He also said that the Al Qaeda hijackers were not responsible for September 11.)

This all happened around the time when his son released “The Passion of the Christ,” a film that Mel Gibson both wrote and directed and that resurrected the canard that Jews share collective guilt for the crucifixion of Christ. Aside from indulging a blood libel, Mr. Gibson’s wayward Catholic beliefs contradicted the Second Vatican Council of 1962-1965, which explicitly warned against reading the Gospels too literally.

At the time, given the salacious nature of the film and his father’s kooky pronouncements, Mr. Gibson was asked to supply his own views on the Holocaust. He went on to begrudgingly fold it within the overall death toll of World War II. “I have friends and parents of friends who have numbers on their arms,” he said, reminding us to beware of anyone who reflexively follows up his bigotry with “some of my best friends are Jews, blacks, and gays.” In the end, the son refused to repudiate the father — perhaps not out of respect but rather ideological consensus.

Indeed, perhaps it’s time to finally concede that “The Passion of the Christ” was not merely a theological dispute framed in aesthetic terms. Whatever its merits, the film, and Mel Gibson’s anti-Semitic Malibu tirade, may be the poisonous fruit from the Gibson family tree. The sins of the father have a way of resurfacing in their sons. When he let his guard down on Friday morning, when he could no longer hide his passion or his rage in the self-exonerating scrim of celluloid, we saw the latest installment of Mel Gibson’s psychic state, a screen test that he shouldn’t be able to pass.

No matter what Gibson now says, it wasn’t the booze that was talking to those stunned police officers who never realized that all of those iconic Gibson screen legends, perhaps, were not acting after all.

Mr. Rosenbaum is a novelist, essayist, and law professor, and the author of the novels, “The Golems of Gotham,” “Second Hand Smoke,” and “Elijah Visible.”