How do we understand the Old Testament? Some would say it is not necessary for the church at all or at least very secondary to the New Testament. Some would go so far as to say it speaks of a different God or God before He became the graceful/loving God of Jesus and the New Testament. What does the Bible say about itself if we allow it to speak on this topic?
The New Testament writers quote often form the Old. When Jesus, Paul, Peter and others speak of scripture they are usually referring to the entirety of what we call the Old Testament. It is in fact only in a few places that we see New Testament writing called scripture (2 Pet. 3:14-16) for example. We know other New Testament writings were treated as scripture largely by the fact that they were given an authoritative role in the early church. But what do we do with what we call the Old Testament?
Jesus gives great insight into this question several times:
John 5:37 And the Father Himself, who sent Me, has testified of Me. You have neither heard His voice at any time, nor seen His form. 38 But you do not have His word abiding in you, because whom He sent, Him you do not believe. 39 You search the Scriptures, for in them you think you have eternal life; and these are they which testify of Me. 40 But you are not willing to come to Me that you may have life. (NKJV) Jesus ensures His audience (self-righteous Jews) that the purpose of the Old Testament scriptures is not to bring salvation by works, but point to the need for and identity of a Savior – Him!
Luke 24:25 Then He said to them, “O foolish ones, and slow of heart to believe in all that the prophets have spoken! 26 Ought not the Christ to have suffered these things and to enter into His glory?” 27 And beginning at Moses and all the Prophets, He expounded to them in all the Scriptures the things concerning Himself. (NKJV) Jesus says the Old Testament writings not only suggest the need for a savior, but ensure and describe the fact/necessity of one based on prophecy and other Old Testament writing about Him!
Luke 24:44 Then He said to them, “These are the words which I spoke to you while I was still with you, that all things must be fulfilled which were written in the Law of Moses and the Prophets and the Psalms concerning Me.” 45 And He opened their understanding, that they might comprehend the Scriptures. 46 Then He said to them, “Thus it is written, and thus it was necessary for the Christ to suffer and to rise from the dead the third day, 47 and that repentance and remission of sins should be preached in His name to all nations, beginning at Jerusalem. 48 And you are witnesses of these things. 49 Behold, I send the Promise of My Father upon you; but tarry in the city of Jerusalem until you are endued with power from on high.” (NKJV) Jesus connects the knowledge of Old Testament truths regarding Himself to the specifics and necessity of His death and resurrection for sin. He further connects the Old Testament and its fulfillment in Him as relevant to both the message of and purpose for future evangelism.
Clearly Jesus saw the Old Testament as describing the need for a savior and pointing to the specific identity and work of that savior. From the fall and expulsion of Adam and Eve, the judgment of the world by flood, the destruction of Sodom and Gomorrah, to the failures and exile of Israel, Jesus sees the entire narrative of human history as His story!
It would seem dangerous and unwise to try to understand the grace of God as found in Jesus Christ without understanding the justice/judgment of God as described in the Old Testament.
The Old Testament is not secondary, not describing a different God, not something to avoid or be embarrassed by, but rather the foundation for understanding the need of salvation as found only in and through the person and work of Jesus Christ.
Does this mean every verse in the Old Testament is specifically about Jesus? Probably not, but it does all speak to the sinfulness of man, the holiness of God and the need for salvation to come form outside the work of men, so in that respect it is all certainly about Jesus. It also holds very specific prophecies of Jesus as well as countless types/shadows pointing to Jesus and His work.
If God’s goal in scripture/history was to save good people He would have to admit complete failure. If God’s goal in scripture/history was to show His holiness/justice as well as His mercy/grace as He redeems a people for Himself solely by His grace through Jesus Christ and all for His eternal glory - then His plan is working perfectly!
Eph. 1:3 Blessed be the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly places in Christ, 4 just as He chose us in Him before the foundation of the world, that we should be holy and without blame before Him in love, 5 having predestined us to adoption as sons by Jesus Christ to Himself, according to the good pleasure of His will, 6 to the praise of the glory of His grace, by which He made us accepted in the Beloved. 7 In Him we have redemption through His blood, the forgiveness of sins, according to the riches of His grace 8 which He made to abound toward us in all wisdom and prudence, 9 having made known to us the mystery of His will, according to His good pleasure which He purposed in Himself, 10 that in the dispensation of the fullness of the times He might gather together in one all things in Christ, both which are in heaven and which are on earth—in Him. 11 In Him also we have obtained an inheritance, being predestined according to the purpose of Him who works all things according to the counsel of His will, 12 that we who first trusted in Christ should be to the praise of His glory. 13 In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also, having believed, you were sealed with the Holy Spirit of promise, 14 who is the guarantee of our inheritance until the redemption of the purchased possession, to the praise of His glory. (NKJV)