The book is so.....complex and rather vague in a lot of ways. That saying, I don't think anyone can correctly say who has the appropriate teaching of the bible and who doesn't.
The bible simply listed stories that was added to it, I don't see it saying what part of it you need to follow or anything. This got me thinking, is the bible even meant to be followed or rather a collection of stories that people didn't want to get lost?
It was probably difficult and costly back in the era to make copies of multiple books with limited technology, and it may have been easier to copy them by lumping them all in one collective book.