In the Rocky films, Sylvester Stallone often starred in a wordless montage of training scenes. It captures something of the thickset biopic Father Stu that the same device is recycled. In place of slog in the boxing gym, however, Mark Wahlberg’s hero Stuart Long preps with prayer. The movie is faith-based, drawn from a true story of devout Catholicism. But it does begin as a fight flick, Long introduced as a roguish pug whose career is ended by bad news from the doctor. It will not be the last time our man receives that. For now, though, drunk and agnostic, he throws a punch at a statue of Jesus.

To Hollywood! As his character sets out to crack Los Angeles and an indifferent film business, you may be reminded of Wahlberg’s turn as an adult movie star in Boogie Nights. In real life, the actor — a believer himself — later expressed unease at having appeared in Paul Thomas Anderson’s profane 1997 ensemble piece. The arc travels elsewhere. A near-death experience inspires a religious conversion, and another career change. The movie transforms into the tale of a kid with a crazy dream — to become a priest, criminal record notwithstanding.

As a hired hand in other people’s movies, Wahlberg can make his boredom visible. His zeal for Father Stu is just as obvious. (His own money went into the budget.) The star’s wild-card charisma motors the story along, even if events sprawl beyond the control of first-time director Rosalind Ross when tragedy enters.

Still, the movie doesn’t lack for bold choices. On the night that Stuart finds Christ, an oddly familiar bearded figure dispenses hard-edged wisdom at a bar. You may be just as struck by the arrival of Mel Gibson, cast as Long’s scowling father, loudly contemptuous of the “nuts” of LA. The whole movie takes such a dim view of the film industry, you may wonder why Gibson and Wahlberg have spent so long making their livings from it. Mysterious ways indeed.

★★★☆☆

In UK cinemas from May 13