What do we do with the Old Testament?
It’s a fair question—after all, we have the New Testament now. And reading the Old Testament can be challenging, to say the least. It was originally written to a different culture with a totally different way of looking at the world…and parts of it are really weird and confusing. So why bother? Does it even apply to us today?
You probably won’t be surprised to discover that the answer is yes, we should read the Old Testament. Here are a few reasons why:

1. It is the foundation of our faith.

In I Corinthians 15:3-4 Paul repeats a particular phrase: “For what I received I passed on to you as of first importance: that Christ died for our sins according to the Scriptures, that he was buried, that he was raised on the third day according to the Scriptures.” When he wrote, “according to the Scriptures,” Paul meant the Old Testament. At this point the New Testament didn’t exist, so when the early church gathered to meet, they would have read the Old Testament. It seems to me, if we’re staking our eternal destiny on Christ, we might really want to get to know these Scriptures.
I should also add that during the time when the church was growing the most—in the book of Acts—they were, surprisingly enough, exclusively reading the Old Testament. Somehow the truth they found within those pages allowed them to change the world.

2. It allows us to understand the New Testament.

The Old Testament is quoted over eight hundred times in the New Testament, and that’s before we start counting indirect quotations and references! If all the different authors of the New Testament thought it was that important—and knew it well enough to quote it frequently—that’s a strong indication that we should spend some time getting to know the Old Testament. Confusing passages in the New Testament often make much more sense if you understand the Old Testament passages they are referencing. If you encounter an Old Testament quote while reading the New Testament, try going back and reading the entire chapter of the Old Testament. You may be surprised by how much that helps you understand what you’re reading in a new way.

3. Jesus relied on it to defeat temptation. 

Jesus used the Old Testament to defeat Satan’s temptations three times (Matthew 4:1-11). Knowing the Old Testament enabled Him to know what God really wanted from Him—what true obedience looked like. It was reliance on the Old Testament that allowed Jesus to counter the lies of Satan. Perhaps if we relied more on it, we might find fresh strength in the words of Scripture to say “no” to temptation!

4. It points to Jesus.

After His death, one of Jesus’ more interesting appearances was on the road to Emmaus (Luke 24:13-35). He appeared to two of His followers and “beginning with Moses and all the Prophets, He explained to them all of what was said in the Scriptures concerning Himself” (v27). If we want to get to know Jesus, we can find Him all throughout the Old Testament. In fact, one of my favorite teachers was persuaded to become a Christian when he investigated the amazing number of Old Testament prophecies that Jesus fulfilled. Believe it or not, Jesus fulfilled roughly 300 of them! If you’re curious, you can read more here.

5. The Old Testament is not obsolete; it is a key part of God’s story that sees its fulfillment in Jesus.

Genesis tells the story of creation—the value of our world and the great worth of humanity, which is the very basis for our understanding of human rights. It also chronicles the fall, introducing the pervasive problem of sin. But that’s not all. 
Throughout the Old Testament we see glimpses of redemption to come. Read the book of Judges and you will see God forgive the people’s sins again and again. Ezekiel and Jeremiah speak of God’s plan to give His people new hearts with His law written on them. Isaiah shows how God’s plan was for the whole world to be saved – that He was concerned about everyone, not just the Jewish people.
God knew all along that we couldn’t save ourselves. He knew it in the Old Testament—it didn’t surprise Him. The Old Testament is the story of our problem and shows us in brutally full color that we need a Savior. Without the Old Testament, we don’t really see why Jesus had to come and die. Without the Old Testament, we don’t see the depths of God’s love and grace for us!
One writer I really like doesn’t even call it the Old Testament; he calls it the First Testament. Testament is another word for “witness.” These books of the Bible are the first witness to us—the witness that we have a sin problem, that God hates sin and loves us, that we need a Savior, and that God planned from the very beginning to send Him to us (Genesis 3:15).
This doesn’t mean that reading the Old Testament is easy or that parts of it aren’t really challenging. But it does mean it’s worth our time to try to understand. If you’re reading the Old Testament and you have questions or you stumble on passages you don’t like, that’s okay! God is big enough to handle your uncertainty. Stop and pray. Ask Him to show you why this story is a part of the Bible. Find another believer who’s been doing this longer, and ask them questions. The Old Testament contains the beautiful first part of the story of God’s love for us.  I pray you read it with that in mind and that you continue “to grasp how wide and long and high and deep is the love of Christ, and to know this love that surpasses knowledge.” (Eph. 3:18-19)