We only know God because He graciously reveals Himself to us. Otherwise we would never discover Him in our fallen state. God’s revelation of Himself has been progressive. All of the previous installments of God’s revelation of Himself have pointed forward to the greatest revelation of all: Jesus Christ.

God’s Revelation in Jesus Christ. Jesus is the Word of God (John 1:1, Hebrews 1:1-3). Jesus is the fulfillment of the Old Testament (OT) Scripture (John 5:39). Jesus quoted and expounded upon the OT Scriptures (Matthew 5-7, Luke 24:27). Jesus is the perfect human image of the Father. He told Phillip (and us), "If you have seen me, you have seen the Father.” (John 14:9; see also Colossians 1:18, Hebrews 1:3).

Jesus testified to the veracity (truthfulness) of the OT revelation: John 5:39. John 6:45 quotes the OT to prove its endorsement of His ministry, using the technical term, “it is written.” In Matthew 4:4 Jesus appeals to every word that proceeds out of the mouth of God.

Jesus testified to the necessity of the OT revelation, that He is the fulfillment of it (Luke 4:21), and that other events will happen so that the Scriptures will be fulfilled (John 13:18-19). Jesus testified that Moses and the prophets spoke of Him (Luke 24:27).

Jesus testified of the integrity of OT revelation. Jesus appealed to the integrity of the whole OT Scripture (John 10:35, Matthew 24:35, John 17:14). Jesus appealed to the integrity of a single word of OT Scripture (Matthew 22:29-32, 42-45). Jesus appealed to the integrity of a single letter of OT Scripture (Luke 16:17, Matthew 5:18). Jesus testified of the integrity of the coming New Testament (NT) Scripture (Matthew 28:20, John 17:17, John 14:26).

Jesus’ ministry and claims concerning Himself were confirmed by His miracles (John 10:25).

God’s revelation of Himself in Jesus is recorded and explained by the Apostles in the NT.[1] Two key NT passages that summarize the witness of the Apostles concerning the inspiration of Scripture are 2 Timothy 3:16 and 2 Peter 1:19-21. Both of these affirm that the OT Scriptures are not the writings of men, but of God. We might say that while men were the secondary writers, God is the Author.

That the Scriptures are inspired by God means they must be inerrant [2] since God is inerrant. That the Scriptures are inerrant means they must be authoritative because God is supremely authoritative (Psalm 115:3).

Notes:
[1] The New Testament is not uniquely new, but is the completion of what the Old Testament spoke of prophetically.
[2] Inerrancy means the Scriptures are “without error.” Infallibility means the Scriptures are “incapable of error.” Both are true of all the Bible, but it is commonly accepted to use the word inerrant to refer to both inerrant and infallible.