It can be easy to get intimidated by the Old Testament. And while there can be confusion about certain things because we don’t immediately understand the cultural context or all of the metaphorical language that gets used, in many ways, it’s more straightforward than the New Testament. To be fair, we should be reading all of God’s word. The point isn’t that one is better than the other. But it can be easy to neglect the Old Testament, and almost have an attitude that it is less relevant in light of the gospel and the New Testament. But remember that in Jesus’ day, what we now call the Old Testament was the scripture. And that scripture mattered to Jesus, and it mattered to Paul, and it mattered to the gospel writers.
Throughout the New Testament, it is difficult to go more than a section or so without getting to verses which are either referencing the Old Testament or directly quoting the Old Testament. A foundation in the Old Testament is essential to being able to more fully appreciate the New Testament.
To illustrate this point, the gospel of Matthew is constantly looking back to the Old Testament with respect to Jesus as a fulfillment of the Old Testament (as are the other three gospels).
In chapter 1, the genealogy is rooted in the Old Testament, and shows God sovereignly working throughout human history to fulfill the promise he made to Abraham and that he continued through the Mosaic Law and with the Davidic Covenant. The events surrounding the birth of Christ: where he’s born, where they travel are also spelled out in the Old Testament. The temptation narrative in the wilderness is steeped in the Old Testament and shows Jesus as the greater Israel, who didn’t grumble and who didn’t fall into sin. The Sermon on the Mount begins with the beatitudes which are rooted in verses of blessing in Isaiah 61. The teaching throughout the rest of the Sermon on the Mount is expanding and elaborating on the ethics of the Old Testament. The miracles Jesus does find their basis in Isaiah, again concurrent with the Messianic Age ushered in through Christ. The passion narrative: his betrayal, his sinless death, the mockery he faced, the brutality he endured are all talked about in the Old Testament.
There can still be texts in the Old Testament which are harder to understand. For that reason, I think it can be helpful to get a good study Bible. While I don’t think we should use study Bibles as a crutch for our own thinking, it can help when there’s a reference which we simply wouldn’t be able to understand otherwise. For me, I like the ESV Study Bible, but there are several which are very good.
Certainly some books in the Old Testament are more difficult than others. But given the prevalence of narrative, it’s often times less theologically dense than what someone would find in Paul. Again, not saying that a person should neglect any portion of the Bible. All scripture is God breathed (2 Timothy 3:16).
A third reason, which goes hand in hand with the Old Testament helping a person to understand the New Testament is that the Bible is an entire narrative showing the greatness of God, his creation of the world, creation of people, humanity’s sin, God’s plan for redemption, while leading up to the life, ministry, death and resurrection of Christ. To undermine the Old Testament is to miss most of the story!
Recap: The Old Testament is God’s word. The entire Bible is the story of God redeeming fallen humanity. The Old Testament helps us understand the New Testament.