Over the years of my study of Scripture, I have come to realize something inescapable: anyone who seriously studies the Bible will inevitably encounter the tension—sometimes subtle, sometimes explicit—between the Old and New Testaments.
As a researcher of the Scriptures, my mission is not to take religious sides, but to understand and expose what the biblical text itself reveals in terms of continuity and rupture between its two great blocks: the Old and the New Testament.
From the beginning, we see a structural harmony between the testaments. Both share characters, prophecies, and fundamental principles about God, justice, sin, and redemption.
However, it is also clear that there are points of friction—and these differences have been debated for centuries by theologians, historians, and biblical scholars.
The Concordances: a line of continuity
Let us begin with the concordances. Both the Old and New Testaments affirm the sovereignty of one God, creator of heaven and earth (Genesis 1:1; John 1:1-3).
The idea that God is just, holy, and demands holiness from human beings is constant. In Leviticus 19:2, we read: “Be holy, for I, the Lord your God, am holy”. Peter, in the New Testament, echoes this same command in 1 Peter 1:16.
Another point of convergence is the centrality of the promise of redemption. From Genesis 3:15, where it is promised that the “seed of the woman will crush the serpent’s head,” to John 3:16, where it is stated that “God so loved the world that he gave his only begotten Son,” there is a thread of messianic hope.
Furthermore, the ethics of the Ten Commandments, given at Sinai (Exodus 20), are reinforced in the New Testament. Jesus, when asked about the greatest commandment, answers based on the Torah: to love God above all things (Deuteronomy 6:5) and your neighbor as yourself (Leviticus 19:18). Matthew 22:37-40 shows how the Master did not come to abolish the Law, but to summarize it in love.
The Disagreements: ruptures and reinterpretations
Despite this structural harmony, there are clear theological and practical disagreements. A classic example is the sacrificial system.
The Old Testament sets out a complex system of sacrifices to atone for sins (Leviticus 1–7), but the New Testament presents Jesus as the “Lamb of God, who takes away the sin of the world” (John 1:29).
In Hebrews 10:4 we read: “For it is impossible for the blood of bulls and goats to take away sins.”, a direct argument against the eternal efficacy of the Mosaic sacrifices.
Another breaking point is circumcision. In the Old Testament, circumcision was the sign of the covenant between God and His people (Genesis 17:10-14).
However, in Galatians 5:6, Paul declares that “in Christ Jesus neither circumcision nor uncircumcision has any value, but faith working through love.” Here, the identity of God’s people is redefined not by outward signs but by faith.
The treatment of ceremonial and dietary laws also contrasts. In the Old Testament, several laws determined what was clean and unclean for consumption (Leviticus 11).
Jesus, however, states in Mark 7:18-19 that “There is nothing outside a man that by going into him can defile him; but the things that come out of him, these are what defile the man.”, and Mark adds: “So he declared all foods clean.” What was once a matter of law is now interpreted as a matter of the heart.
Ruptures that point to a greater purpose
Even in its disagreements, the New Testament often presents itself as the fulfillment of the Old. In Matthew 5:17, Jesus states: “Do not think that I have come to destroy the Law or the Prophets. I have not come to destroy but to fulfill.” The idea here is one of fullness, not opposition.
It is as if the old covenant was a shadow of what would come to fruition in the new one.
As I studied the Pauline letters, I noticed that Paul often interprets the Law as pedagogical, a “schoolmaster” leading to Christ (Galatians 3:24-25).
With the coming of Christ, the purpose of the Law is fulfilled and, therefore, its normative function loses its original force. Justification, which was previously associated with obedience to the Law, is now by faith (Romans 3:28).
Conclusion: progressive harmony or theological contradiction?
As a researcher, I see that the answer depends on the perspective adopted. If we read the Bible as an organic whole, we see a narrative and theological progression in which the New Testament does not contradict the Old, but interprets it in light of the coming of Jesus.
On the other hand, if we isolate the texts, some contradictions become evident and difficult to reconcile.
Ultimately, the relationship between the Old and New Testaments can be described as one of promise and fulfillment, shadow and reality, foundation and building.
The tension remains—and perhaps it is this tension that makes the study of Scripture so fascinating and vital. As someone who seeks to understand, not just believe, I continue to explore this rich and sometimes paradoxical territory.