The authority of the Word of God rests squarely upon the authority of Jesus Christ himself. As a believer you fully accept Jesus Authority, being the Word of God.

In the beginning before all time was the Word and the Word was with God, and the Word was God Himself. (John‬ ‭1:1‬) And the Word, Who is Christ, became a human man, and lived awhile among men; and men actually saw His glory, the glory of the One and Only who came from the Father overflowing grace, tender mercy and truth. (John‬ ‭1:14‬)

Christ Jesus is the image of the invisible God, His Divine portrait, and true likeness (Colossians‬ ‭1:15‬) He was the one all things were made and and nothing was brought brought into existence without him. (John 1:3) In Him all things were created, in heaven and on earth, things seen and things unseen, whether thrones, dominions, rulers, or authorities; all things were created and exist through Him and in and for Him. (Colossians‬ ‭1:16‬ ) He existed before anything was made, and now all things consist of your help together by him. (Colossians‬ ‭1:17‬)

The Father has spoken to us in through His Son, Whom He appointed Heir and lawful Owner of all things, also by and through Whom He created the worlds and the reaches of space and all time. (Hebrews‬ ‭1:2‬) He holds the universe together and expands it by the mighty power of his spoken word.
‭‭(Hebrews‬ ‭1:3‬)