I kind of wondered about why they needed to interact with a physical copy of the "bible" too. Hell, you'd think there'd be a digital copy in the shuttle or something. But maybe it's just some aspect of the religion that it has to be in book form and only certain books are considered "true" versions so only one in a ship. (And we just have to accept though "TV magic" that Ed was able to use his Not!Tricorder to capture an image of all of the pages of the book in a short length of time. Though, at the end of the episode they don't need the images as they now have an actual, physical, copy of the book.