The bible claims it is the word of God.
Paul wrote to young pastor Timothy, “All Scripture is given by INSPIRATION of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness…” — 2 Timothy 3:16
The word “Inspiration” in the original language literally means, “God Breath.” In other words, God spoke His words to the heart of the writers and they wrote what God inspired them to write.
Additional verses to consider.