Occasion of Sin/An

``Do you canonize a rich and ambitious son of a bitch who bought ecclesiastical promotion at the same time as he was carrying on a lifelong romance with another man's wife?'' That's for Father Laurence McAuliffe (last seen in The Cardinal Virtues ) to discover in Greeley's engrossing new mixture of intrigue, politics, sex and, of course, churchly issues. Shortly after John Cardinal McGlynn, archbishop of Chicago, dies in a volley of gunshots in Nicaragua, the grandson of his longtime companion, Marbeth Quinlan, is miraculously cured of terminal cancer. A popular cult arises around the cardinal's memory, and there talk of canonization. McAuliffe is enjoined to find anything in ``Jumping Johnny's'' background that might be less than saintly. In the process, McAuliffe, who never liked the charming but somewhat shallow Johnny, travels around the world, becomes immersed in Vatican politics and is put on the trail of Solidarity's early funding in Poland. But the most troubling mystery is the ambiguous relationship between Johnny and Marbeth, the wealthy dowager who admits she's loved Johnny since she was a child. Also puzzling is the change that came over Johnny two years before he died and led him to martyrdom. As McAuliffe tracks down all those involved in Johnny's life, he learns the true nature of sainthood and, in the surprise ending, undergoes a change himself. Although the elements here are standard Greeley, this novel, besides being entertaining, suspenseful and well researched, is also more serious than it sounds. Literary Guild and Doubleday Book Club main selections. (June)