Guterson (”Snow Falling on Cedars”) is a meandering writer — a trait that often works brilliantly. But his new novel begins with a surprising dramatic bang: Ann Holmes, an itinerant mushroom picker in Oregon, has a vision of the Virgin Mary. Soon a cult forms around her, and we’re off and racing into ”Mariette in Ecstasy” land…or not. Alas, Guterson doesn’t have a racing bone in his body, with the exception of the sudden let’s-wrap-things-up ending. It’s the only jarring piece of an otherwise thoughtful, if occasionally plodding, rumination on faith and human frailty.