Why do Christians have both an Old Testament and a New Testament?

The presence of both the Old Testament and the New Testament in the Christian Bible is deeply rooted in the concept of covenant, a foundational theme that runs throughout the entire biblical narrative. The term "testament" itself is derived from the Latin word "testamentum," which translates the Greek word "diatheke," meaning "covenant." Therefore, when we refer to the Old and New Testaments, we are essentially speaking of the Old and New Covenants.

In the Bible, a covenant is a solemn agreement between God and His people, often involving promises, stipulations, and signs. The Old Testament, or Old Covenant, primarily refers to the agreements God made with the people of Israel, while the New Testament, or New Covenant, speaks to the new relationship God has established with humanity through Jesus Christ.

The Old Testament: The Foundation of God's Promises

The Old Testament is rich with various covenants that God made with His people, each serving as a building block in His divine plan for humanity. The first significant covenant is the one God made with Noah after the flood, symbolized by the rainbow (Genesis 9:8-17). This covenant was a universal promise that God would never again destroy the earth with a flood.

Next comes the Abrahamic Covenant, where God promises Abraham that he will be the father of a great nation, that his descendants will inherit the land of Canaan, and that through him, all the nations of the earth will be blessed (Genesis 12:1-3, 15:1-21, 17:1-14). This covenant is crucial because it sets the stage for the coming of the Messiah, through whom the ultimate blessing for all nations would come.

The Mosaic Covenant, given through Moses at Mount Sinai, is another pivotal moment. Here, God provides the Law, including the Ten Commandments, and establishes Israel as His chosen people (Exodus 19-24). This covenant is conditional, based on Israel's obedience to God's laws. The sacrificial system and the priesthood are also introduced as a means for atonement and maintaining the relationship between a holy God and a sinful people.

The Davidic Covenant further narrows the focus to the lineage of King David, promising that his throne will be established forever (2 Samuel 7:12-16). This covenant is messianic, pointing forward to Jesus Christ, who is often referred to as the Son of David in the New Testament.

The New Testament: Fulfillment and Transformation

The New Testament is the record of the New Covenant, which was prophesied in the Old Testament and fulfilled in Jesus Christ. The prophet Jeremiah spoke of a new covenant that would be different from the one made with the ancestors of Israel when they were brought out of Egypt (Jeremiah 31:31-34). This new covenant would involve the law being written on the hearts of the people, and their sins being forgiven and remembered no more.

Jesus Himself inaugurated this New Covenant during the Last Supper, where He took the cup and said, "This cup is the new covenant in my blood, which is poured out for you" (Luke 22:20). Through His sacrificial death and resurrection, Jesus fulfilled the requirements of the Old Covenant and established a new way for humanity to relate to God. This New Covenant is based on grace rather than law, faith rather than works, and it is available to all people, not just the descendants of Abraham.

The Apostle Paul elaborates on this in his letters, particularly in the book of Romans and Galatians. He explains that the law was a tutor to lead us to Christ, but now that faith has come, we are no longer under a tutor (Galatians 3:24-25). Paul also emphasizes that in Christ, there is neither Jew nor Gentile, slave nor free, male nor female, but all are one in Him (Galatians 3:28). This universality of the New Covenant is a significant departure from the national focus of the Old Covenant.

Continuity and Discontinuity

While the Old and New Testaments represent different covenants, there is both continuity and discontinuity between them. The continuity lies in the fact that the New Covenant fulfills the promises and prophecies of the Old Covenant. Jesus did not come to abolish the law but to fulfill it (Matthew 5:17). The moral and ethical teachings of the Old Testament still hold value, but they are now understood through the lens of Christ's life, death, and resurrection.

The discontinuity is seen in the shift from the old sacrificial system to the once-for-all sacrifice of Jesus. The book of Hebrews elaborates on this, explaining that the blood of bulls and goats could never take away sins, but Christ's sacrifice is sufficient for all time (Hebrews 10:1-18). The priesthood has also changed; Jesus is now our high priest, who intercedes for us before the Father (Hebrews 4:14-16).

Theological Implications

The existence of both the Old and New Testaments in the Christian Bible underscores several important theological truths. First, it highlights the faithfulness of God. Despite human failure and disobedience, God remains committed to His promises. The covenants reveal a God who is both just and merciful, holy and loving.

Second, it demonstrates the unfolding nature of God's revelation. The Old Testament lays the groundwork, providing the historical and theological context for the coming of Christ. The New Testament reveals the fullness of God's plan, showing how the promises of the Old Testament are realized in Jesus.

Third, it emphasizes the importance of Scripture as a unified whole. While the Old and New Testaments have different emphases and contexts, they together tell the comprehensive story of God's redemptive work in history. This unity of Scripture is crucial for understanding the character of God and His purposes for humanity.

Practical Applications

For Christians today, having both an Old and New Testament is essential for a well-rounded faith. The Old Testament teaches us about God's character, His creation, and His dealings with humanity. It provides wisdom, poetry, prophecy, and history that are invaluable for understanding the human condition and God's expectations for us.

The New Testament, on the other hand, provides the revelation of Jesus Christ, the foundation of Christian faith. It offers the teachings of Jesus, the acts of the apostles, and the theological insights of Paul and other writers, which are crucial for living out the Christian life.

Both Testaments together help believers understand the full scope of God's salvation history. They guide us in worship, ethics, and mission, showing us how to live in a way that honors God and reflects His love to the world.

In conclusion, Christians have both an Old Testament and a New Testament because they represent the two major covenants that God has made with humanity. The Old Testament lays the foundation, revealing God's character and His initial promises. The New Testament fulfills and transforms these promises through the life, death, and resurrection of Jesus Christ. Together, they provide a comprehensive and unified revelation of God's redemptive plan, guiding believers in faith and practice.