Nora Gallagher has written two memoirs about her Christian faith, and other pieces have appeared in the New York Times Magazine, the Washington Post, and Mother Jones. In Things Seen and Unseen: A Year Lived in Faith, she presents an account of her experiences at Trinity Episcopal Church in Santa Barbara, California, focusing on her involvement as a regular worker at the soup kitchen, as a member of a Thursday evening base community, as a lay Eucharistic minister, and as a participant in alternative liturgies. "Church is both familiar and a foreign planet," she wrote. In her second book, Practicing Resurrection: A Memoir of Work, Doubt, Discernment, and Moments of Grace, Gallagher's faith is challenged and stretched over a three-year period in which she deals with the death of her brother, a discernment process to decide whether she has been called to the priesthood, and a study year at a parish.

Changing Light is Nora Gallagher's first novel. It is a love story and thriller set in the summer of 1945 against the creation of the atom bomb at Los Alamos. It deals with the strange and yet powerful confluence of the lives of three people in Santa Fe, New Mexico: a physicist who is having second thoughts about his work on "the gadget," as the bomb is called; a woman artist pursuing an independent life; and an Episcopal priest who is obsessed with her. These fascinating characters enable Gallagher to probe the manifold mysteries of the human heart, the joys of creativity, the delights of science, and the meaning of faith. And in these four thematic arenas, we can see the beginnings of the ethical challenges that dog our days and stir our spirit in the present era.

Eleanor is a painter from New York City whom one art critic has called "an American (female) Matisse." But a clash with her older husband Edgar, who runs a gallery, has sent her to Santa Fe where she has lived for the past three years. The landscape on the ten acres where she lives speaks to her soul.

She has struck up a relationship with Bill Taylor, pastor of All Saints Episcopal Church, a man of faith who loves gardening. He likes talking to Eleanor and knows that she is a talented and special person. Taylor also enjoys games of chess with David, a quiet fellow who doesn't talk very much about his work as a machinist. At one point, the priest ponders:

"Every person was a mystery. . . .Almost every person had a secret. The secret was often tied up with each person's destiny, not to be confused with a preordained destination. No, it was more complex than that. It was as if each of us had another, deeper life than the one being lived. It lies underneath our ordinary days, our errands, the doing of dishes, the writing of letters, the making of money, like something moving, lobsterlike, under water."

Father Taylor has his secrets, and so does Eleanor. But the man with the biggest secret of all is Leo Kavan, a foreigner whom Eleanor finds lying ill near her house. He claims to have gotten lost while camping. But eventually Eleanor learns that he is a physicist who walked off the Los Alamos project following the death of his closest associate. Although they come from completely different worlds, Leo and Eleanor have something in common: those they love are beyond their reach. He does not know what has happened to his sister Lotte, and her brother Theodore is in a Japanese prison camp. Realizing that he doesn't have much time, Leo starts a campaign to speak out against the use of the atom bomb against Japan. But Eleanor's talk to Father Taylor about his stay at her house puts his advocacy in jeopardy.

Gallagher's novel is suffused with Christian terms and rituals. The characters reflect upon prayer, faith, grace, and resurrection. The imagery of light plays a major role in the story as Eleanor tries to delineate the light of the place where she lives, the scientist wonders about the consequences of his work on the bomb which gives off blinding light, and the priest learns a little about the light of love. And these lights change as the characters interact with each other.