“If there was an omnipotent Supreme Being, why would He use such a fallible device of communication--a book written by men, selected by men? Why not just communicate directly?”
God did communicate directly with human beings. When He gave the Ten Commandments, the nation of Israel was so fearful that they thought they would die. He has chosen to give us His written Word telling us how to find everlasting life, and we are to simply do what it says.