My best guess would be that there is such a wide divergence of belief in the Christian churches is that we, as Believers, tend to try and bend things, including the Word of God, to our own choosing and liking. A lot like the "itching ears" referred to in Scriptures. People can't agree on things non-spiritual, so it would stand to reason that we can't agree on things spiritual. It is true that God is Eternal and Christ unchanging, but we humans waver and change. It is a sad commentary to the Faith that we Believers can't agree on the most important area of our lives. Very good question!