Comedian Gad Elmaleh has been called “the Seinfeld of France,” and based on his latest movie, “Stay With Us,” having its premiere Friday at the Quad Cinema, the appellation is both apt and not completely accurate.

Like Jerry Seinfeld, Mr. Elmaleh is able to tease out comedy from everyday moments and trivialities, yet his film is certainly not about “nothing,” as “Seinfeld” the sitcom has been labeled. Centering on a middle-aged Jewish man converting to Catholicism, its story explores questions of faith and religion and even ponders the unknown, which in some ways could be considered “nothingness,” but the movie never succumbs to pretension or solemnity, maintaining a level, blessedly irreverent head.

As it turns out, the story is very personal to Mr. Elmaleh, and though the film is not a documentary, the comedian appears as himself, as do his real parents and sister and other nonfictional characters. In press notes, the comic/writer/director explains that he’s always been fascinated with Mary, the mother of Jesus, and it’s this pull that drives the narrative. These autobiographical and factual elements lend the fictional film an easygoing authenticity while also giving it a certain self-consciousness that never devolves into wink-wink overstatement. It’s all very meta and amusing.

Voiceover by Gad at the start of the film informs us of how he was born at Casablanca into a traditionalist Sephardic Jewish family. Long a city where different faiths have enjoyed autonomy and acceptance, he nonetheless mentions that Jewish and Muslim children were forbidden to enter into churches. This prohibition leads the young Gad to develop an intense curiosity about Christian temples, eventually entering one as a child, an event that his sister recounts to his parents a little later in the film. 

Back to the beginning, though: Home movie footage of the young Gad’s home life taken by the senior Mr. Elmaleh segues seamlessly into current-day scenes of his mother and father in their real-life Parisian apartment. After a stint in America, Gad is back in France and goes to see his parents. Mr. Elmaleh’s well-observed, gently comical touch is everywhere: in his pause at his parents’ door as he hears them squabble inside; in how his carrying of a plastic bag marks him out as a Moroccan; in how his mother leaves a chocolate on his bedroom pillow to mimic hotel luxury. He has no intention of staying with his parents, but his mother is not easily refused and so he agrees to do so one night — which becomes several weeks.

Some viewers will see elements of themselves and their own parents in this wry portrayal of the Elmaleh family, in how his parents see Gad as both a successful adult and as still a child. Yet it’s not until his parents find a statuette of Mary in Gad’s suitcase that the movie ups its subtly farcical ante. Gad will be baptized in five weeks but hasn’t told his parents for fear of their reactions. Soon, at a shabbat dinner given by his cousin, what starts off as humorous quickly turns serious when the truth is disclosed. Said cousin reminds Gad of the history of the Sephardic Jews in Catholic Spain and emphatically dismisses Pope John Paul II’s apology for the church’s inaction during the Holocaust. Mercifully, Mr. Elmaleh never forgets to entertain and ends the scene with a pretty funny, thematically related physical joke.

Throughout the movie, Mr. Elmalah the director intersperses scenes of him doing standup (another reference to “Seinfeld”) and of him in a pool practicing the act of baptism. These aren’t as funny as they could have been and probably should have been edited out, but they don’t take away from the consistently nimble comic range of the film’s scenario. 

As Gad prepares for his conversion, and his parents attempt to comprehend their son’s decision, the picture progresses from one droll moment to the next, from lightly delivered broad humor about money and political punchlines referencing Donald Trump and Jean-Marie Le Pen, to playfully profane jokes and pseudo-Freudian analysis of Gad’s obsession with Mary. There’s even a shot of a pro-and-con list in which Gad puts “Never work with Spielberg again” in the con column. (Mr. Elmalah was the voice of Omar ben Salaad in director Stephen Spielberg’s animated “The Adventures of Tintin.”)

In its final stretch, after Gad meets a young Catholic worshiper and her elderly charge, and as he converses with a Talmud teacher and a rabbi, “Stay With Us” loses some of its springiness by getting into the weeds of belief, doubt, and fate. Still, the film effectively explores how the two faiths — Judaism and Christianity — share deep roots. After all, both Jesus and Mary were Jewish. And while the “will he or won’t he convert” climax ends up a forgone conclusion, there’s always Mr. Elmalah’s earnestness and the keen sense of the absurd he shares with Mr. Seinfeld, allowing both to surprise and delight. The unique alchemy he achieves in his film demonstrates that the banal, the ludicrous, and the heartfelt often stem from the same sect.