The problem is not with only the belief of the King James Bible only. The belief in a literal Genesis in fundamentalist Christianity is rooted historically in the King James only belief. At present about 40% to 50%+ of the Christians in the US believe in a literal Genesis, and a fundamentally literal Bible.
To add: This has it's roots in the beliefs of the Church Fathers concerning the scriptures and in particular Genesis.
It's hard enough to understand the Bible in a language that you axually speak. Trying to comprehend divine wisdom from the King James version is like trying to learn Spanish from a textbook written in French.