That God cannot lie or speak falsely is the essence of the authority of Scripture (2 Samuel 7:28; Titus 1:2). His words must always be trusted. This is the very essence of what authority is. Hebrews 6:17-18 mentions two immutable things: the promise and oath of God, “in which it is impossible for God to lie”. Therefore all the words of Scripture are completely true and without error in any part (which speaks to infallibility). “Every word of God proves true; he is a shield to those who take refuge in him.” (Proverbs 30:5) With regard to authority, God’s words are the ultimate standard of truth. In John 17:17 Jesus prays “sanctify them by Your truth; Your word is truth.” Note that Jesus does not say “Your word is true”. He does not use an adjective but rather a noun (aletheia), to say that God’s word is not simply “true”, but that it is truth itself. This is significant because it establishes for us that the Bible is not simply “true” in the sense that it conforms to some higher standard of truth, but rather to understand the Bible as being itself the final standard of truth. Therefore, written Scripture is our final authority (1 Corinthians 14:37, 2 Timothy 3:16).
That the Bible will not lead us astray in matters of faith and practice is the essence of the infallibility of Scripture (Acts 24:14; Luke 24:25; Romans 15:4; 1 Corinthians 10:11). Infallibility says that the Bible is absolutely reliable. The texts just listed affirm that every part of Scripture is to be trusted and relied on completely. Infallibility and authority are very tightly related to each other. Scripture must be infallible due to the very nature of authority. If Scripture is truth, then it necessarily follows that it must be without fault or error either at any particular point or in any idea expressed. Therefore, the doctrine of infallibility flows logically out of the doctrine of authority and the doctrine of authority is in its many applications supported by the doctrine of infallibility.
If the Bible is fallible and contradicts itself, then there is no way to know what it means. In any given instance Scripture might mean exactly the opposite of what it says. If Scripture might mean the opposite of what it says, then there would be no way of knowing what the Bible intends for us to believe and do. If we can’t know what the Bible intends for us to believe or do, then in the most real and practical sense, it has no authority over our lives because we can’t know what it wants from us. A self-contradictory Bible undermines knowledge (epistemology), which undermines authority (ethics).
