Out of all the troubling beliefs of C.S. Lewis, his view of Scripture is probably the one that should cause Christians the greatest concern. In fact, what you will find is that many of his other theological errors find their root in his deficient theology of the Word of God. It is not as though Lewis did not value the Bible or submit his thinking and writings to the Scriptures, because he actually believed that the Bible truly is the Word of God. However, if you try to understand what exactly he meant by the ‘Word of God’ you will start to find problems.
For one, Lewis believed that some portions of Scripture were more inspired than other portions and he understands inspiration as God exerting his divine compulsion on the biblical authors differently. He says, “There are prophets who write with the clearest awareness that Divine compulsion is upon them. There are chroniclers whose intention may have been merely to record. There are poets like those in the Song of Songs who probably never dreamed of any but a secular and natural purpose in what they composed.” It is hard to tell if the authors of Scripture knew to what degree they were under divine compulsion as they wrote, but the problem with Lewis is that he is claiming that the more aware the author was of divine compulsion, the more inspired were his writings. This is a dangerous error since it hinges the inspiration of Scripture in the understanding of man as opposed to will and mind of God.
This mistake leads Lewis to categorize different portions of Scripture on a continuum of divinity. He categorizes the words of Jesus as being the most inspired, the Apostle Paul’s writings a little lower, and the rest of Scripture lower still. If you try to understand how he arrives at that decision, you will find something close to Neo-orthodox presuppositions. Lewis believes that the Bible “carries the Word of God” which means God uses texts that were written by men to accomplish His purposes. Now God certainly does use the Bible to accomplish His purposes but the issue lies in that Lewis believed the Bible to be the Word of God only when it was being used by God for a specific purpose. This is incredibly similar to the doctrine of inspiration that Karl Barth taught which is essentially that the Bible becomes the Word of God. Both of these views are unbiblical and contrary to the orthodox position that the Bible is the Word of God.
The orthodox and biblical position is called plenary verbal inspiration which essentially teaches that every word in the Bible is directly inspired by God and therefore the Scriptures, as a whole and in particular, are the Word of God. This doctrine is grounded all throughout the Scriptures but most clearly in 2 Timothy 3:16 where Paul says that “All Scripture is God-breathed.” In other words, the orthodox understanding is not that the Bible has the ability to become or carry the Word of God, but that the entire Bible was directly inspired by God himself. The Bible’s words are God’s words.
 Lewis, C. S. Reflections on the Psalms. 1st edition. (New York: Mariner Books, 1964), 109.
 Lewis, Reflections, 111.
 Ibid, 113.
 Ibid, 112.
 Christensen, Michael J. C. S. Lewis on Scripture: His Thoughts on the Nature of Biblical Inspiration, The Role of Revelation and the Question of Inerrancy. (Nashville: Abingdon Press, 2002), 87.
 Alcorn, Randy, Philip Graham Ryken, Kevin J. Vanhoozer, and Douglas Wilson. The Romantic Rationalist: God, Life, and Imagination in the Work of C. S. Lewis. Edited by John Piper and David Mathis. (Wheaton, Illinois: Crossway, 2014), 42.
 Alcorn et al., Romantic Rationalist, 43.