Have you ever read the Christian book Pilgrim's Progress?

It is somwhat boring. It's worth reading if you have to do it (I did) but I would not choose to do so. The language is modern English not Old English (that was about 800 years earlier) and the book was written some seventy years after Shakespeare and the King James Version of the bible. If you can understand the KJV, you will certainly understand Bunyan.