Somewhere through the centuries, people have come up with the idea that the differences between the first covenant (Old Testament) and the renewed covenant (New Testament) are law versus grace, obedience versus faith, and an angry God versus the gospel of a loving Jesus. Nothing could be further from the truth. You will find law and grace, obedience and faith, and the wrath of God and the gospel of Jesus in both testaments. This is because there is one consistent God throughout all of scripture, throughout all of eternity.
First of all, let’s let Scripture define the new covenant. Hebrews 8:10, “For this is the covenant that I will make with the house of Israel after those days, said the LORD; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people.” What is it that he will put in our minds? His laws. Now, how can anyone logically say that the law only applies to the old covenant, when having the law in our hearts and mind is the basis of the new covenant?
Similarly, it is unscriptural to conclude that people in the OT were saved by law, when it is clear that they were saved by grace through faith. Flip a few more pages in your Bible to Hebrews 11. It was by faith that Abel offered a more excellent sacrifice, and by faith that Enoch was translated that he should not see death. Verse six says that without faith it is impossible to please God. It was by faith that Noah built the ark, and by faith that Abraham offered Isaac. The list goes on: Isaac, Jacob, Joseph, Moses’ parents, Moses, Joshua, Rahab, and more than the writer of the book of Hebrews can state.
The Old Testament is full of stories about sinners who were saved by grace through faith, and not a single one that was saved by keeping the law. Let’s look again at the list of those referenced in Hebrew 11. We have Noah (drunkenness and nakedness caused sin), Abraham (didn’t wait on God’s promise so conspired with Sarah to get Hagar pregnant), Jacob (tricked his father into giving him Esau’s blessing), Moses (killed the Egyptian), Rehab (a prostitute), Samson (lust for Delilah caused him to sin), and David (an adulterer and murderer). I feel like I’m airing their dirty laundry, but yet these stories should give us hope. Who among us hasn’t sinned?
But the biggest reason that we should realize that the Old Testament is just as much about faith and grace as the New Testament is that we can share the gospel of Jesus Christ using only the Old Testament. Refer to Luke 24:44. On the road to Emmaus, Jesus teaches them that what was written in “the law of Moses, and in the prophets, and in the psalms” was concerning him. He also said in John 5:46, “For had ye believed Moses, ye would have believed me: for he wrote of me.” We see in Acts 8:32, 35 that Phillip brought the eunuch to Christ through explaining the book of Isaiah. We see in Acts 17:2 that Paul reasoned with the Jews out of Scriptures to bring them to Christ, and in Acts 17:11 that the Bereans searched the scriptures daily to see if what Paul taught about Jesus being the Messiah was true. As a side note: Every time you see the word “scriptures” in the New Testament, (about 50 times) it always refers to the Old Testament, because the New Testament did not exist when this was written. Each time, it establishes the validity of the Old Testament after the resurrection of Christ.
If you want to read some wonderful words about Jesus, a few of the many places His own words tell us we can start are: the five books of Moses (also called the Torah, Genesis through Deuteronomy); the book of Isaiah, especially chapter 53; Psalm 22 (the Psalm of the Cross); Psalm 23 (the Resurrection Psalm) and Psalm 24 (the Ascension Psalm).
As a post script to those who are thinking, “Well, then what is the difference between the Old and New Testaments?”, it is forgiveness by the blood of animals versus by the blood of Jesus. See Hebrews 9:12-28.