What is the difference between the Old Covenant and the New?

When people talk about the Old Testament and the New Testament, they usually mean two halves of one book. But the Bible itself talks about two covenants, and that is a different question. What changed between them, and why did God promise a second one at all?

The first covenant did not open with a rule. It opened with a rescue.

I am the Lord thy God, which have brought thee out of the land of Egypt, out of the house of bondage.

Everything God asked of Israel came after that sentence, not before it.

God made the first covenant with a rescue already done

At Sinai, God did not negotiate with slaves. He had already parted a sea and buried an army. Only then did He offer terms: keep my voice and my covenant, and "ye shall be a peculiar treasure unto me above all people" (Exodus 19:5), "a kingdom of priests, and an holy nation" (Exodus 19:6). Israel answered as one voice, twice: "All that the Lord hath said will we do" (Exodus 24:3, 24:7). Then Moses sprinkled blood on the people and said the words that hold the whole scene together.

Behold the blood of the covenant, which the Lord hath made with you concerning all these words.

Grace came first. The requirement came second. That order never reverses in Scripture, and it will matter again in a moment.

That covenant was carved in stone and kept as a witness

The terms of the first covenant were not vague. They were written with the finger of God on two tables of stone (Exodus 31:18, Exodus 34:28) and placed inside the ark. The book of the law went in beside it, and Moses told the Levites exactly why.

Take this book of the law, and put it in the side of the ark of the covenant of the Lord your God, that it may be there for a witness against thee.

A witness against thee. The law sat outside the people, testifying to what they had not done. That was never a flaw in the wording. It was the location of the problem, and it is the exact thing the next covenant was written to fix.

Jeremiah said the next covenant would not be like that one

Centuries later, while the first covenant still stood, God spoke through Jeremiah about a covenant that had not happened yet.

Behold, the days come, saith the Lord, that I will make a new covenant with the house of Israel, and with the house of Judah: Not according to the covenant that I made with their fathers in the day that I took them by the hand to bring them out of the land of Egypt; which my covenant they brake, although I was an husband unto them, saith the Lord: But this shall be the covenant that I will make with the house of Israel; After those days, saith the Lord, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people. And they shall teach no more every man his neighbour, and every man his brother, saying, Know the Lord: for they shall all know me, from the least of them unto the greatest of them, saith the Lord: for I will forgive their iniquity, and I will remember their sin no more.

Four promises, stated plainly. The law moves inside a man instead of standing outside him. Every one of God's people knows Him personally, without a teacher standing in the middle. Iniquity is forgiven. Sin is not just covered - it is not remembered. Ezekiel says the same thing from the inside out: a new heart, a new spirit, God's own Spirit put within them (Ezekiel 36:26-27).

Jesus took the words of Exodus 24 and poured them into a cup

On the night He was betrayed, Jesus did not invent new language. He reached back to Sinai.

Likewise also the cup after supper, saying, This cup is the new testament in my blood, which is shed for you.

Moses had said, "Behold the blood of the covenant" (Exodus 24:8). Jesus said, this is the new covenant, in blood. Hebrews points out that the first covenant was dedicated with blood too (Hebrews 9:18-20). Same word. Same shape. A different blood, and it does not need repeating.

Hebrews says the first covenant was a shadow, and the Law still has work to do

Hebrews calls Jesus "the mediator of a better covenant, which was established upon better promises" (Hebrews 8:6), and does not soften why the first one needed replacing.

For it is not possible that the blood of bulls and of goats should take away sins.

The old sacrifices were repeated every year for the same reason a bandage is repeated every day. They covered; they did not cure. Christ offered one sacrifice for sins for ever (Hebrews 10:14) and sat down, because the work was finished.

None of that means the Law is thrown out. Jesus said He came "not to destroy, but to fulfil" (Matthew 5:17). The law is still "holy, and the commandment holy, and just, and good" (Romans 7:12); it still gives "the knowledge of sin" (Romans 3:20). What changed is not what the law says. What changed is who bears the penalty, and where the law lives.

Not that we are sufficient of ourselves to think any thing as of ourselves; but our sufficiency is of God; who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.

Not in tables of stone. In fleshy tables of the heart (2 Corinthians 3:3).

Where sincere Christians differ

Jeremiah's new covenant is made explicitly "with the house of Israel, and with the house of Judah" (Jeremiah 31:31), which raises a real question: who is this covenant for?

Covenant theology holds that God has run one covenant of grace through all of Scripture, that the Church is the continuation of Israel, and that Israel's promises are fulfilled in the Church. New Covenant theology holds that the law of Moses is set aside entirely in Christ, and the believer answers only to the law of Christ. Dispensational theology holds that Israel and the Church are distinct peoples of God, that the new covenant was made with Israel and Judah and will be fulfilled with them in the coming kingdom, and that the Church shares in its spiritual blessings now, through Christ, without replacing Israel.

We hold the third view. God has not cast off His people (Romans 11:1-2). "The gifts and calling of God are without repentance" (Romans 11:29). Believers today, Jew and Gentile alike, are already "able ministers of the new testament" (2 Corinthians 3:6) - but the covenant's full, visible fulfillment with the house of Israel still waits on the kingdom.

So what is the difference between the old covenant and the new?

Same God. Same law. Same call to holiness.

A different mediator. A different sacrifice, offered once instead of every year. A different place for the law to live - first on stone, now on the heart.

Sin remembered every year under the first covenant. Sin remembered no more under the second.

The blood changed, and everything changed with it.

That is not a small difference. It is the difference between a covenant you keep and a covenant that keeps you.