The Cause is a funny name for a spiritual movement. It sounds like a nice way of putting a disease. “Honey, we have to talk. I’ve got . . . the Cause.” Which is to say it sounds like a nice way of putting a disease in 1950. That’s the year in which Paul Thomas Anderson has set most of “The Master,” a title that could now refer to the scope and grandeur of his filmmaking. More immediately, it’s how some followers of the Cause address Lancaster Dodd (Philip Seymour Hoffman), the charismatic fellow who created it and doesn’t appear to be done determining its particulars, like, namely, what it is. To that end, he turns a feral young naval veteran into his test subject.

The gamble of a movie like this, a film that takes it upon itself to question the limits and possible emptiness of belief, is that it, too, could be dull and meaningless. But Anderson knows what he’s doing. Nothing as big and strange and right as “The Master” should feel as effortless as it does. That’s not the same as saying that it’s light. It’s actually heavy. It weighs more than any American film from this or last year. It’s the sort of movie that young men aspiring to write the Great American Novel never actually write.

Anderson began his career as a dazzling overreacher. His first four films — “Hard Eight,” “Boogie Nights,” “Magnolia,” “Punch-Drunk Love” — were notable for their mania, for the way both the camera and the story would tornado around until he found a moment of biblical postmodernism; until, say, it rained frogs; until you wanted to prescribe him something. With “There Will Be Blood,” it was as if he’d broken up with his approach to filmmaking. That look-at-me dazzle was gone. The hazy influences were clearer and more appropriate. He no longer yearned to be Robert Altman or replicate the 1970s. He was 35 in 2007, but his soul was 62. He was Stanley Kubrick. He was John Huston. He was Abel Gance . The punk was a better classicist. “The Master” continues this new phase of serious social themes; reasonably direct narrative; sublime, almost architectural framing; goose-pimple soundscapes. “There Will Be Blood” turned the dawn of the industrial age into a kind of horror film about ambition’s deranging power. “The Master,” which was shot in oil-painterly 70mm, pursues the deranging power of faith.

The persistent assumption about the film is that it’s the story of Scientology. This may well be what Anderson intends. There are some similarities between Lancaster Dodd and L. Ron Hubbard, the writer, philosopher, scientist, theologian, and seaman who, in the early 1950s, was sharpening Dianetics and the tenets of Scientology. But, more generally, the film is interested in a cult of personality. Like Anderson’s previous movie, “The Master” is a portrait of megalomania. By the time he is introduced, aboard a midsize ship that serves as the site of his daughter’s wedding, Dodd has already built a following around the Cause and its belief in past lives and its aim of erasing old trauma. Its members furnish him and his wife, Peggy (Amy Adams), with access to trinkets of their affluence — boats, homes, that sort of thing — for the privilege of calling him Master and throwing private soirées where the Master massages up their recovered memories.

Dodd takes a glorifying interest in Freddie Quell (Joaquin Phoenix), the itinerant sailor from Lynn, who stumbles onto Dodd’s pleasure cruise while the ship is docked one night in San Francisco. Dodd could be drawn to the drifter’s stooped posture, slurred way with language, wizened face, and general uncouthness — everything about him says “fix me.” There’s also no underestimating the appealing challenge of conquering the demons of a man whose name is Freddie Quell. Though, the truth about their bond might be simpler than any of that. Freddie is an alcoholic, and Dodd likes the poisonous drinks Freddie concocts. When asked whether his cocktails, which contain everything from gasoline and cleaning agents to developing fluid, are lethal, Freddie’s rattled response is, “Not if you drink it smart.” For his part, Dodd might be the first man, besides Freddie, to ingest this stuff and not keel over. One man thinks he’s found a friend. The other bypasses friendship and sees experimental possibilities. Dodd calls Freddie a silly animal, and in this silly animal the Cause has a cause.