How can the Bible be God’s Word if it was written by human authors? This is a common question that arises when discussing the supernatural origin of the Bible. It is true that the Bible was written across 1600 years of human history by more than 40 human authors. How can it still be written by God? Paul tells Timothy that “All scripture is given by inspiration of God” (2 Timothy 3:16). “Inspiration” is the Greek word theopnuestos which literally means “God-breathed.” Jesus corroborates this when he said that we live by “…every word that comes from the mouth of God’ ” (Matthew 4:4). The men who wrote the books of the Bible wrote under divine inspiration and the end result is the words of both the human author and of God.
There are differing theories of how God inspired the biblical authors. Most conservative, evangelical Christians believe in what is call “verbal plenary inspiration.” The word verbal affirms that the very words the writers chose are inspired. For example, in Acts 1:16 the Apostle Peter says “the Holy Ghost by the mouth of David spake” (KJV). The word plenary means “full” or “complete” meaning that God inspired the complete text of the Bible, including historical, scientific, and doctrinal details. This concept of how God inspired the Bible is seen in Peter’s words, “For no prophecy was ever produced by the will of man, but men spoke from God as they were carried along by the Holy Spirit” (2 Peter 1:21, ESV). Although men put the pen to paper, the things they wrote did not originate in their brains, but in the heart of God. God inspired the writers, they transmitted the message.
Some of the authors might not have realized at the time that they were writing the words of God. However, many did know this. Gordon R. Lewis writes, “Over 3,000 times biblical writers claimed to have received their messages from God. God the Holy Spirit “inspired” (breathed out or originated) the Scriptures through the human writers (2 Tm 3:16).God prepared these conscious, active prophetic and apostolic spokesmen (and their secretaries) providentially by their heredity, character, vocabularies, and writing styles. At the appropriate time, in all the processes of writing, they were “moved by the Holy Spirit” (2 Pt 1:21).” 
The Holy Spirit guided the human authors while allowing their individual personality, knowledge, and vocabulary to produce the books of the Bible. The end result is the very Word of God communicated through the medium of human writers. This view recognizes both the human and divine aspect of Scripture.
 Cabal, T., Brand, C. O., Clendenen, E. R., Copan, P., Moreland, J., & Powell, D. (2007). The Apologetics Study Bible: Real Questions, Straight Answers, Stronger Faith (1812). Nashville, TN: Holman Bible Publishers.