The Word must be the final authority in your life. According to the book of the John, in the beginning the Word was present. In the book of Genesis this is evident; God created this world by the Word. Throughout the OT the prophets of God spoke about the Coming Messiah. Isaiah in Is 53:1 spoke about these prophecies challenging the people on believing the word that God sent through them accompanied by His power.
When God speaks it should be final in our lives. And when it is and we walk in His Word, His power which backs up that Word is evident.