I read comments like this one from believers quite frequently, and always in the same context: an effort to impeach the opinion of an unbeliever regarding scripture. That's quite a claim considering that the Bible is not a technical book like a law or physics book, and thus contains no technical jargon, just plainspeak. Yet for some reason, we are told that ordinary people just can't understand it notwithstanding the fact that it cobbled from oral tradition intended for ordinary people to understand, believe, and obey. The punishment for failing to understand the words and therefore failing to obey them was often quite severe.
You didn't make the same comment about Harry Potter, which is similarly written to be understood by everybody, and generally is. Nor do we see this claim made about any other book written in ordinary, conversational language. King James English might be a bit stuffy, but there are more modern translations available in modern English.
Much of it is vague, but it is easy to see that immediately, and vague language has no definite meaning anyway, even if its author intended it to. That which is clear is easily understood, even where it is incorrect or contradicts passages elsewhere.
It's my experience that unbelievers are a far better source of information about what biblical scripture says and means simply because they are free to read it impartially, and feel no need to rectify the apparent deficiencies. Unbelievers are free to comment on problems in the Bible that the believer is quick to sweep away, usually by adding something to scripture, or altering its apparent meaning.
For example, when an unbeliever reads the Book of Job, he comes away from it having read about a god that trifled with the life of a good man as a demonstration to a demon of that man's faith, a demonstration that including killing his children. The unbeliever finds that story problematic. The behavior of the deity is cruel and immoral, and serves no purpose. I expect that if you read that story in a book like Aesop's Fables rather than your Bible, that you would agree that the story is as I described it.
The believer, however, reads that story in his Bible and goes to work to make the story make sense according to his understanding of God. I had a collection of explanations from believers that I can no longer locate. One told me that Job wasn't actually a good man, and that the punishment was deserved. Another told me that God was training him for something greater. These explanations are all just made up by the individual believer to have the story support the idea that God is good. This is why I say that if you want to know about the Book of Job without reading it yourself, and yes, it is very easy for any literate person to read and understand as written, you should go to an unbeliever for the unaltered version of the story.