Curtis, a longtime editor at The Atlantic Monthly, has gathered a provocative sampling of modern fiction dealing, in some fashion, with the brambly issue of faith. Some of the 30 stories here focus on a protagonist's uneasy relationship with God; in Andre Dubus's mournful tale ""A Father's Story,"" a decent, devout man is driven by his love of his daughter to break both temporal and divine laws by helping her cover up the fact that she had struck and killed a pedestrian. His suffering, and his resolution, are beautifully etched. Bernard Malamud's haunting ""Idiots First"" follows the frantic efforts of the dying Mendel to raise enough money to send his handicapped son on to relatives. In this effort he feels himself pursued by God, and during a final confrontation with his deity, both God and man discover unexpected elements in each other. ""Parker's Back,"" by Flannery O'Connor, offers that author's patented, masterful, unique mix of elements: Parker, a ne'er-do-well anxious to work his way back into his regnant wife's good graces, decides to have a portrait of Jesus tattooed on his back, certain that his devout wife will take him in as a result. Instead, in a scene mingling farce and despair, she's horrified and belabors him with a broom. ""Grace,"" by James Joyce, creates an unsparing portrait of the ways in which faith mingles with more unseemly motivations in the lives of a group of struggling businessmen. Stories by Cynthia Ozick (""Rosa""), William Trevor (""Autumn Sunshine""), and Philip Roth (""Defender of the Faith"") are equally strong and varied. It's only by contrast with these distinctive tales that some of the others seem less imaginative and resonant. Still, the best pieces here are so very good, and cover so many viewpoints in their exploration both of the origins of faith and our uncertain, often anxious negotiations with a deity, that they make this a useful, moving, often stimulating collection.