The ""Saint"" is the notorious Marquis de Sade whose satanical debaucheries and orgiastic philosophy and writings became the underground delight of Europe. In this fictionalized biography Mr. Endore attacks his subject with all the relish that the Marquis must have shown when putting a knife to his victims. Unfortunately the form he has chosen, ""something like a novelized Ph.D. thesis,"" is painfully confusing. The novel proceeds chronologically in the form of ""quotes""-- i.e. letters, diaries, extracts from books and documents from the Marquis' family, acquaintances, police records and the Marquis' notorious books, but the author has ""occasionally scissored them, squeezed them here and fattened them there, contouring them to the necessities of my unfolding story and even when necessary inventing them."" This leaves the reader wallowing in a ""true or false?"" cross-word puzzle. But students of de Sade will find some of Mr. Endore's interpretations intriguing, particularly since he views his subject so sympathetically, reflecting that the Marquis was essentially a theologian and representing him as tortured rather than torturer. A blunt-edged biography.