"He had in his Bronx apartment a lodger less learned than him..." — Herman Wouk quote meaning

He had in his Bronx apartment a lodger less learned than himself, and much fiercer in piety. One day when we were studying the laws of repentance together, the lodger burst from his room. "What!" he said. "The atheists guzzles his whiskey and eats pork and wallows with women all his life long, and then repents the day before he dies and stands guiltless? While I spend a lifetime trying to please God?" My grandfather pointed to the book. "So it is written," he said gently.—"Written!" the lodger roared. "There are books and there are books." And he slammed back into his room.