To millions of Americans fascinated by comic-book superheroes, Bill Jemas of Princeton is an industry legend who helped breathe life into Marvel Enterprises by pushing the wildly successful “Ultimate Spider-Man” series that rejuvenated the company. These days, however, Jemas, a high-energy 51-year-old whose controversial four years as Marvel’s president remain fodder for comic-book blogs, finds himself engrossed in a task far removed from dialogue balloons. Each morning before sunrise, for the last three years, the Rutgers and Harvard Law School graduate has labored over the Bible, specifically the Book of Genesis in Hebrew, the language in which it was first...