What led this great American artist to make a story of missionaries in Japan his ultimate passion project? He is known for his gangster pictures; he is a grandmaster of the profane. From the beginning, he has revealed himself to be an artist of intensely Catholic preoccupations, and the poisoned arrow of religious conflict runs straight through his career. “Taxi Driver”: a Vietnam vet as a spiritual avenger, bent on cleansing the city of filth through violence. “Cape Fear”: a tattooed fundamentalist determined to exact God’s justice. “Kundun”: a young man raised to be a spiritual master, thrust up against spirit-killing communism. Even “Living in the Material World,” Scorsese’s documentary about George Harrison, takes as its theme the conflict between flesh and spirit, between Beatle and seeker.

“Silence” is a novel for our time: It locates, in the missionary past, so many of the religious matters that vex us in the postsecular present — the claims to universal truths in diverse societies, the conflict between a profession of faith and the expression of it, and the seeming silence of God while believers are drawn into violence on his behalf. As material for Scorsese, then, “Silence” is apt, and yet Scorsese’s commitment to it has been extraordinary, even by his exacting standards. To understand that commitment, I spoke with the filmmaker, with members of the cast and the production team and with others who know the novel well — trying to grasp just what kind of an act of faith this film is.

“I don’t know if there’s redemption, but there is such a thing as trying to get it right,” Scorsese said to me, in the ungentrified New York voice familiar from the cameos in his movies. “But how do you do it? The right way to live has to do with selflessness. I believe that. But how does one act that out? I don’t think you practice it consciously. It has to be something that develops in you — maybe through a lot of mistakes.”

He had invited me to his East Side townhouse at 9 p.m., having spent a full day editing “Silence” in Midtown. The living room, high-ceilinged, oak-paneled, is decorated with a vintage movie camera, billboard-size posters for Jean Renoir’s “The Grand Illusion” and photographs of his wife and daughter. He is 74, compact and gray, with tremendous life in his eyes and a youthful ardor that seems to have its source in reverence for his elders — like the Polish filmmaker Andrzej Wajda, who had signed a storyboard that Scorsese unhooked from the wall to show me. We took seats, and he began to talk. As the hours passed, the room, already dark, seemed to diminish around us, until it resembled a screening room, or a chapel, a place where questions of how to live are posed through stories and images.

“It goes back to what Father Principe was telling me the last time I saw him, a couple of years ago,” he said. “Failing, doing something that is morally reprehensible, that is a great sin — well, many people will never come back from that. But the Christian way would be to get up and try again. Maybe not consciously, but you get yourself into a situation where you can make another choice. And that’s the situation Rodrigues is in” — he can choose to save the lives of others by renouncing his faith, the act he considers most reprehensible of all.

“Silence,” no less than Scorsese’s informal New York trilogy — “Mean Streets,” “Taxi Driver,” “Raging Bull” — is rooted in his childhood. As a boy in Little Italy, he wanted to be a missionary. His parents were not religious, in part because their parents had felt the church’s heavy hand in Sicily, but for him the church — a malign force in so many coming-of-age stories — was a portal to the world beyond family and neighborhood. “I trusted the church, because it made sense, what they preached, what they taught,” he said. “I understood that there’s another way to think, outside the closed, hidden, frightened, tough world I grew up in.”