In 2004, Marilynne Robinson, a legendary teacher at the Iowa Writers’ Workshop, returned to novels after a 24-year hiatus and published “Gilead,” which won a Pulitzer Prize, a National Book Critics Circle Award and a spot on best-of-the-year lists everywhere. It’s hard to imagine those accolades meant much to the Midwestern Calvinist, but four years later she published a companion novel called “Home,” which won the Orange Prize and more enthusiastic praise. And now comes “Lila,” already longlisted for the National Book Award, involving the same few people in Gilead, Iowa, “the kind of town where dogs slept in the road.”

These three exquisite books constitute a trilogy on spiritual redemption unlike anything else in American literature. (Our Puritan forefathers wrote and worried plenty about salvation, but they had no use for novels.) In a way that few novelists have attempted and at which fewer have succeeded, Robinson writes about Christian ministers and faith and even theology, and yet her books demand no orthodoxy except a willingness to think deeply about the inscrutable problem of being. Her characters anticipate the glory beyond, but they also know the valley of the shadow of death (and they can name that Psalm, too). In “Home,” the Rev. Robert Boughton struggles to save his wayward son from drinking himself into the ground. In “Gilead,” the Rev. John Ames, with just a few months to live, races to compose a long letter about his life before he’s carried away to imperishability. And in this new novel, we’re finally, fully engaged with Lila, the unlikely young woman who marries Rev. Ames late in life and gives him a son when he feels as old as Abraham.

The geography and the cast of characters are mostly familiar, but this time around we’re entering a wholly different spirit. Boughton’s alcoholic son may have been lost, but he knew the terms of perdition and could torment his father and Ames in a language they all spoke. Lila crawls into Gilead from another world altogether, a realm of subsistence living where the speculations of theologians are as far away — and useless — as the stars.

The novel opens in a fog of misery. Lila is just 4 or 5, sickly, dressed in rags, when a woman named Doll steals her from her violent home. “Doll may have been the loneliest woman in the world,” Robinson writes, “and she was the loneliest child, and there they were, the two of them together, keeping each other warm in the rain.” They survive by joining up with a tough band of migrants looking for work as the country slides further into the Depression. It’s a vision of failing America somewhere between “The Grapes of Wrath” and “The Road” — poverty grinding away every element of pride until the group fractures under the strain. Robinson has constructed this novel in a graceful swirl of time, constantly moving back to Lila and Doll’s struggles with starvation, desperate thieves and vengeful relatives. We see that dark past only intermittently, as a child’s clear but fragmentary memories or a trauma victim’s flashbacks.

In the novel’s present, Lila, now an adult, almost feral with fear and apprehension, wanders into Ames’s church. In that moment, the old pastor dares to imagine he might be allowed to fall in love again. But Lila is not easily or quickly drawn away from the life she knew. “Happiness was strange to her,” Robinson writes. “When you’re scalded, touch hurts, it makes no difference if it’s kindly meant.”

”Lila” by Marilynne Robinson. (FSG/FSG)

This may be the most tentative, formal and charming romance you’ll ever encounter. Ames, who assumed his years of loneliness would never end, floats off the ground in a state of anxious delight, always preparing himself for the day when Lila will run back out of his life. And everything about the reverend baffles her. “You’re just the strangest man,” she tells him when she knows she’s “horribly in love.” There seems no end to his concerns, his senseless courtesies. “He always helped her with her chair,” she thinks, “which amounted to pulling it out from the table a little, then pushing it in again after she sat down. Who in the world could need help with a chair?” He and his friends talk about people she doesn’t know and things she doesn’t understand. His constant allusions to the Bible — that old book — mean nothing to her. She can’t get over how enthusiastically his congregation sings “songs to somebody who had lived and died like anybody else.”

And yet she considers the reverend’s theological arguments with dead seriousness. Robinson, for all her philosophical brilliance, captures clearly and without a trace of condescension the mind of an uneducated woman struggling to comprehend why things happen, what our lives mean. “She knew a little bit about existence,” Robinson writes in this miraculous voice that somehow blends with Lila’s. “That was pretty well the only thing she knew about, and she had learned the word for it from him.” Lila doesn’t have the luxury of speculating about the possibility of hell; she’s lived there. “She had thought a thousand times about the ferociousness of things so that it might not surprise her entirely when it showed itself again.” The Bible is a revelation to her — though not in the way it is to her husband: “She never expected to find so many things she already knew about written down in a book.” The images of desolation and abandonment in Ezekiel don’t sound to her like history or metaphor — they sound like yesterday. Job could easily have been someone she knew on the road. When Boughton refers to the elect and the damned, Lila fears she may never see Doll again, and wonders if heaven is worth that sacrifice. How is it, she wonders, that these men can worship a God willing to send so many fine people to hell?

“You ask such interesting questions,” Ames says.

“And you don’t answer ‘em,” Lila shoots back. She’s been trained by years of violence and hardship not to trust anyone, but “he was beautiful, gentle and solid, his voice so mild when he spoke, his hair so silvery white.” Can she, dare she, give up the clarity of her old life for this gracious man who loves her past all reason? She knows it’ll only be a matter of time before she shocks “all the sweetness right out of him.”

“Are we getting married, or not?” Ames asks her early in the novel.

“If you want to, it’s all right with me, I suppose. But I can’t see how it’s going to work,” Lila says. “I can’t stay nowhere. I can’t get a minute of rest.”

“Well, if that’s how it is, I guess you’d better put your head on my shoulder.”

For all the despair and trauma that haunt Lila, her story is one of unimaginable, sudden good fortune that only her husband’s patience can coax her into accepting. “I can’t love you as much as I love you,” Lila says with a paradox worthy of St. Paul. “I can’t feel as happy as I am.” Both of these unlikely lovers have suffered enough “to know that this is grace.”

Anyone reading this novel will know that, too.

Charles is the editor of Book World. He reviews books every Wednesday in Style. You can follow him on Twitter @RonCharles.

LILA

By Marilynne Robinson

Farrar Straus Giroux. 261 pp. $26