What is the difference between the Old and New Testaments?

The Old and New Testaments are not two separate books about two different Gods or two different ways of salvation. They are two acts of one unified story — the same God, the same plan, the same ultimate basis of salvation, but at different stages of its unfolding.

The Old Testament covers creation, the fall, God's calling of Abraham and the nation of Israel, the Mosaic covenant and the law, the history of Israel, and the prophetic promises that pointed forward to the coming Messiah. It is the story of God establishing a people through whom He would bless the world.

The New Testament is the fulfilment of everything the Old Testament pointed toward. Jesus said in Matthew 5:17: "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfil them." The New Testament is not the replacement of the Old — it is its completion, its full flower, the reality to which the shadows were always pointing.

The relationship between the two Testaments can be expressed several ways:

The Old Testament is promise; the New Testament is fulfilment. The sacrifices of the Old Testament were shadows pointing to the once-for-all sacrifice of Christ (Hebrews 10:1-14). The priesthood of Aaron was a pattern pointing to the eternal high priesthood of Jesus (Hebrews 7). The tabernacle and temple were copies of the heavenly reality (Hebrews 8:5).

Salvation in both Testaments is by grace through faith. Abraham was justified by faith (Romans 4:3), not by law. The law was never God's mechanism of salvation — it was given to define sin, govern Israel as a nation, and point to the need for Christ (Galatians 3:24).

The Old Testament is essential reading for the Christian. You cannot understand the New Testament without it. The New Testament assumes familiarity with the Old — its language, its promises, its patterns. Jesus opened the disciples' minds to understand the Scriptures after the resurrection, "beginning with Moses and all the Prophets" (Luke 24:27). He did not start with a blank page; He started with what they already had.