No one will be declared righteous in his sight by observing the law; rather, through the law we become conscious of sin.
If you've ever heard of history, then you'd understand that the Old Testament happened a long time ago. Therefore, it's often hard to see the relevance or importance of it all. Especially when we have a much newer version, the New Testament.
And it's even more difficult to parse the meaning and significance of the laws, specifically those in Exodus, Leviticus, and Deuteronomy. After all, there are a lot of crazy ones! This has led me to always wonder about this hidden corner of the O.T. Do I have to follow these? Do they contradict the N.T.? What does it mean!
Here's a portion of Albert Baylis's From Creation to the Cross. He wonderfully illustrates the meaning, the function, and ultimate fulfillment of O.T. law and how it relates to N.T. teaching and our own lives here in the 21st century.
The Laws Function
The law is "holy, righteous, and good" (Rom. 7:12). The law was our tutor to bring us to Christ. (Gal. 3:23-4:7). The Law was added to the promise "because of transgressions until the Seed to whom the promise referred had come: (Gal. 3:19). The Law was not opposed to the promises of God. (Gal. 3:21). The Mosaic Covenant was good, but it had a temporary function. It did not change God's way of working or make his promise based on works. It was a positive program for a time when things needed to be spelled out, when safeguards were needed to protect Israel from falling easily into Canaanite practices. The Law was like a disciplinarian in charge of your training as a minor. When you are older you are disciplined and understand the reasons for manners and lessons, you don't place yourself under the old rules, good as they were. You operate out of your full understanding.
The Law as Scripture
So we are not "under the law" as our operating covenant with God. Paul was opposed to any of his Gentile converts subjecting themselves to the Law either by circumcision or symbolic observances (Gal. 4:10-11, 5:2-3) But Paul is not opposed to using the Law for instruction. It was from his pen that 2 Timothy 3:16-17 flowed, affirming that all Scripture, because it is inspired by God, is to be used for teaching. The Old testament, including the Law, was the Bible of the NT Church. It was not disposed of as a modern tossable - used once and discarded. Nor was it treated as a museum piece for historic interest only. It was still Scripture. And though everything in it was no longer directly applicable, it still could instruct when used with full understanding of its place and purpose.
The Fulfillment of the Law
At the same time Jesus denied any wish to abolish the Law or the Prophets, he also predicted their fulfillment (Matt. 5:17-18). The most minute part of the Law would not pass away "until everything is accomplished." Jesus himself brings the Law to fulfillment in a number of ways. First, he fulfills the sacrificial system. Second, he fulfills the righteousness of the Law. Paul insists that he is upholding it our establishing it, not nullifying it. The righteousness of the Law is not established by keeping it for merit before God. That is doomed to failure. The righteousness of the Law is established by receiving the gift of righteousness by faith in Christ. (Rom 9:30-33). Christ is the end of the Law not only because he inaugurated a new covenant to replace it, but because he achieved its righteous standard for all who believe. Christ satisfies the righteous demands of the Law. It is in him that we "become the righteous of God" (2 Cor. 5:21)
Our focus is not the keeping of the Law as a merit system, but Jesus Christ himself. Our response is based on gratitude for what God has done in Christ.