This gathering of 26 stories by well-known writers on the nature and function of faith is more intriguing for the questions it poses than for any answers it offers. After all, fiction is more about gathering evidence than about arriving at succinct solutions. That said, there are some moving and persuasive tales here, such as Andre Dubus's ``A Father's Story,'' about a man who violates the tenets of his religion to save his daughter; John L'Heureux's terse ``The Expert on God,'' concerning a priest compelled, while ministering to a dying man, to confront his own uncertainties about the nature of faith; Flannery O'Connor's stunning tale ``Good Country People,'' about a devout, crippled woman and a deranged Bible salesman; and Isaac Bashevis Singer's angry ``Gimpel the Fool,'' offering a terse commentary on both this world and the next. Other writers here include Zora Neale Hurston, Vladimir Nabokov (``Christmas''), John Updike, Reynolds Price, and E.M. Forster. A useful and sometimes provocative gathering.