My guess would be that the left ones are old and difficult to read books professors like precisely because of that, and the right are books which explain things in a more understandable way. But that’s just a guess based on that that’s exactly how I, as a former physics major, would use this meme for physics books.

But it’s not about that for many people. For many people, being religious is more about finding strength and peace in that kind of guided spirituality