Old vs. New Covenant: Understanding the Shift in God’s Plan (Jeremiah 31:31-34)

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📖 Old vs. New Covenant: Understanding God’s Redemption Plan

The transition from the Old Covenant to the New Covenant is one of the most profound shifts in biblical history. Why was a New Covenant necessary? How does it transform our relationship with God? Let’s unpack Jeremiah 31:31-34, exploring how Jesus’s Last Supper fulfilled prophecy and established a better covenant for believers.

The Brennan Center for Justice is a nonpartisan law and policy institute. They published an article titled Prison and Jail Reform. Here’s a surprising part of the second sentence of the article: “Prisons often provide little to no effective rehabilitation.” This is an astonishing admission from a secular research institute about the ineffectiveness of our prison system!

Why don’t prisons work? There is a saying that the heart of every problem is the problem of the heart. Prisons don’t work because they don’t deal with people’s hearts.

Lasting Change Must Begin with the Heart

If punishment could change people’s hearts, we could provide prison sentences long enough for inmates to return to society as model citizens when released. The best example in Scripture of punishment not changing the heart:

Genesis 6:5 The Lord saw that the wickedness of man was great in the earth, and that every intention of the thoughts of his heart was only evil continually.

That is an incredible indictment. Things were so bad that God had to flood the earth. I can’t imagine a worse punishment than a global flood, which is to say that if a punishment could change man’s heart, a global flood should. The water subsided. Noah and his family got off the ark. Noah built an altar and offered burnt offerings to God. Then we read:

Genesis 8:21 And when the Lord smelled the pleasing aroma, the Lord said in his heart, “I will never again curse the ground because of man, for the intention of man’s heart is evil from his youth.

This is what God said in His heart, which means it isn’t my, Noah’s, or Abraham’s. Even this catastrophic punishment didn’t change man’s heart. Not long after the flood, what sins do you start seeing? Polygamy, incest, prostitution, and homosexuality.

So you ask, “If the flood wouldn’t change man’s heart, what was the point?” God didn’t bring the Flood to change man. He brought the flood to remove the demonic influence in the world, and it worked. You don’t see demonic influence again until Christ’s First Coming, when the demonic realm flared up against the kingdom of God coming from heaven to earth.

If punishment could change hearts, what parents wouldn’t keep spanking their children until their hearts changed? We hope punishment, whether prison systems or spanking, is a deterrent and provides outward change. But we would be foolish to think it provides any change inwardly. Only the Gospel can do that.

The Heart’s Importance

Proverbs 4:23 Above all else, guard your heart, for everything you do (all outward behavior) flows from it.

That is incredible. We are not told that some things we do, or even most, flow from our hearts. Everything we do flows from our hearts. All outward behavior originates inwardly. The way we talk, act, dress, you name it, if it is external, it came from the heart.

Consider these two statements from Christ. First:

Matthew 15:19 Out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander.

This is a pretty exhaustive list of sins. I’m almost surprised Jesus mentioned so many. It seems to be His way of letting us know all sins come from the heart. If all sin comes from the heart, the only way to change what happens on the outside is to change what’s on the inside.

The second statement from Christ:

Matthew 12:34 Out of the abundance of the heart the mouth speaks.

If we said it outwardly, it originated inwardly. I remember having my mouth washed out with soap. We can wash our kids’ mouths with soap, but we better ensure we do something for their hearts. The only way to truly clean up children’s dirty mouths is by cleaning their dirty hearts; soap can’t do that.

Consider this teaching:

Matthew 12:43 “When the unclean spirit has gone out of a person, it passes through waterless places seeking rest, but finds none. 44 Then it says, ‘I will return to my house (referring to the person the demon previously left) from which I came.’ And when it comes, it finds the house empty, swept, and put in order. 45 Then [the unclean spirit] goes and brings with it seven other spirits more evil than itself, and they enter and dwell there, and the last state of that person is worse than the first.

The words swept and put in order mean the person looks good outwardly. They have removed the unclean spirit or habitual sin from their lives. In other words, they look like they have changed. But the word empty means that nothing has changed inwardly. They have the same heart, so they end up worse than before. And isn’t this often the case: When the drug addict stops taking drugs, but then uses again, don’t they consume more than they did before? Isn’t it the same with alcohol, pornography, lying, anger, covetousness, you name it?

The Old Covenant Didn’t Change the Heart

Let me give you another example from Scripture that might surprise you: the Old Covenant. The Old Covenant dealt with people’s outward behavior, but not with their hearts, so it didn’t produce change. I’m not criticizing the Old Covenant:

Romans 7:12 The law (referring to the Old Covenant) is holy, and the commandment is holy and righteous and good.

Paul’s assessment of the Old Covenant couldn’t be better. So, if the Old Covenant isn’t the problem, what is? We are! The Old Covenant, or the Mosaic law, provided a holy and righteous standard, but our flesh, or sinful nature, prevents us from keeping it.

The Old Covenant Reveals Our Sinfulness

So you say, “Then why did God give us the Old Covenant?” The law, or Old Covenant, does something essential: reveal our sinfulness:

Romans 3:20 By works of the law no human being will be justified (or declared righteous) in [God’s] sight, since through the law comes knowledge of sin.

If we didn’t have the law, or Old Covenant, we wouldn’t understand how sinful we are and how much we need Christ. God could justly condemn us to hell for eternity for failing to keep the law, or Old Covenant, but because He is gracious, He established a New Covenant so that now there is another way to be saved:

• Under the Old Covenant, we could be justified or declared righteous by keeping the law perfectly, something nobody but Jesus has ever accomplished.
• Under the New Covenant, we can be justified or declared righteous by grace through faith in Jesus Christ.

The Most Important Verses in the Old Testament

I think verses that provide the greatest foundation for New Testament doctrine are the most important. For example:

Genesis 15:6 Abraham believed the Lord, and he counted it to him as righteousness.

This is the primary verse used to defend justification by grace through faith, which is to say it’s the primary verse to defend the gospel. It is quoted in Romans 4:3, Galatians 3:6, and James 2:23.

A close second is:

Habakkuk 2:4 the righteous (or just) shall live by faith.

This verse also lays the foundation for the gospel. It is quoted in Romans 1:17, Galatians 3:11, and Hebrews 10:38.

Psalm 110:4 The Lord has sworn and will not change his mind, “You are a priest forever after the order of Melchizedek.”

This verse defends Jesus’s priesthood. The priests were supposed to be from the tribe of Levi, but Jesus was from the tribe of Judah. This would prevent Jesus from being our High Priest if not for Psalm 110:4, which says the Messiah would be from the Melchizedekian priesthood.

If there were an essential passage, I would argue that it’s Isaiah 53 because it’s filled with the language of substitutionary atonement. It’s quoted in Matthew, John, Romans, Acts, and 1 Peter and alluded to in many other places.

Finally, there are the verses that prophesy the New Covenant. The importance of these verses cannot be overstated:

Jeremiah 31:31 “Behold, the days are coming, declares the Lord, when I will make a new covenant with the house of Israel and the house of Judah, 32a not like the covenant (referring to the Old Covenant) that I made with their fathers on the day when I took them by the hand to bring them out of the land of Egypt,

We will break up this verse into a few parts to unpack it.

Jeremiah 31:32b my covenant that they broke,

This summarizes man’s relationship to the Old Covenant, but it is almost misleading because the word broke is singular. Israel broke the law repeatedly. Moses couldn’t even make it down the mountain with the law before the people broke it.

Now, because of our flesh, or sinful nature, we like to make excuses and shift blame, so God said:

Jeremiah 31:32c though I was their husband, declares the Lord.

This shows that Israel’s disobedience or unfaithfulness can’t be blamed on God. He has been as faithful as a husband should be to his wife.

Six Ways the New Covenant Is Not Like the Old Covenant

God said the New Covenant is not like the Old Covenant. Here are the six most important ways they differ.

Unlike the Old Covenant, Under the New Covenant, God Does the Work

Even though we don’t deserve it, look what God graciously does:

Jeremiah 31:33 For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people.

The Old Covenant is conditional, so it is filled with the phrase, “If you:”

• “If you obey, this will happen…”
• “If you disobey, this will happen…”

The Old Covenant didn’t work because it was conditional on us. If the New Covenant were also conditional on us, we would fail under it. So, God made the New Covenant unconditional: instead of being about what we must do, it is about what He will do. There are seven “I will statements”:

1. 31a I will make a new covenant…
2. 33a This is the covenant that I will make…
3. 33b I will put my law within them…
4. 33c I will write it on their hearts…
5. 33d I will be their God…
6. 34a I will forgive their iniquity…
7. 34b I will remember their sin no more.

Second, Unlike the Old Covenant, Under the New Covenant, the Focus Is Inward

In verse 33, God said, “I will put my law within them, and I will write on their hearts.”¹ Earlier, I talked about the importance of changing the heart, and that’s what God does through the New Covenant. The Old Covenant was outward and physical, written on stone tablets (Exodus 24:12, 31:18, 32:15, 16, 2 Corinthians 3:3, 7). The New Covenant is inward, written on man’s hearts. Consider this verse:

2 Corinthians 3:3b You are a letter from Christ delivered by us, written not with ink but with the Spirit of the living God, not on tablets of stone but on tablets of human hearts.²

Paul distinguished between the Old and New Covenants by pointing out the New Covenant’s ability to deal with the heart. Ezekiel is the other prophet who spoke the clearest about the New Covenant. Consider what He said:

Ezekiel 11:19 I will give them one heart, and a new spirit I will put within them. I will remove the heart of stone from their flesh and give them a heart of flesh,

Ezekiel 36:26 I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your flesh and give you a heart of flesh.

Again, we see God doing the work. The phrase “I will” occurs six times in these two verses, and the focus is on the inward with the heart: “I will give you a new heart, and a new spirit I will put within you…I will remove your heart of stone…I will give you a heart of flesh.”³

Third, Unlike the Old Covenant, Under the New Covenant, the Holy Spirit Teaches Us

Jeremiah 31:34a And no longer shall each one teach his neighbor and each his brother,

To fully appreciate verse 34, we must understand that under the Old Covenant, the priests were the teachers:

Leviticus 10:8 The Lord spoke to [the priests] saying…11 you are to teach the people of Israel all the statutes that the Lord has spoken to them by Moses.”

In the Old Testament, if you wanted to learn about God, you went to the priests. But, under the New Covenant, the Holy Spirit is our teacher:

John 14:26 The Helper, the Holy Spirit, whom the Father will send in My name, He will teach you all things, and bring to your remembrance all things that I said to you.

John 16:13 When the Spirit of truth comes, he will guide you into all the truth, for he will not speak on his own authority, but whatever he hears he will speak, and he will declare to you the things that are to come.

Human teachers aren’t abolished under the New Covenant. Ephesians 4:11 and 1 Corinthians 12:28 list teachers as one of the office gifts for the church, and Romans 12:7 lists teaching as one of the gifts of the Holy Spirit. But you don’t need human teachers like the Old Testament saints needed priests. There are great spiritual benefits associated with sitting under biblical teachers, but if you were alone on an island with the Word of God, you could learn God’s Word with the Holy Spirit as your teacher.

Fourth, Unlike the Old Covenant, Under the New Covenant, Christ is the Only Mediator

Jeremiah 31:34b saying, ‘Know the Lord,’ for they shall all know me, from the least of them to the greatest, declares the Lord.

This doesn’t seem a big deal because we talk about knowing the Lord. We ask, “Does he know the Lord?” or “Does she know the Lord?” But this would have sounded like a huge deal in the Old Testament because people didn’t know the Lord personally. They only knew Him through priests. This is why the priests were called mediators.

I hate to say it, but the Old Testament was somewhat like the Catholic Church today: I didn’t feel like I knew the Lord personally while in the Catholic Church. I understood that if I wanted to approach the Lord, I had to do so through my priest, Mary, or the saints.

This is why the priests were spread throughout the land, so all the people could access them as mediators between themselves and God. But under the New Covenant, we read:

1 Timothy 2:5 There is one God, and there is one mediator between God and men, the man Christ Jesus,

Coming out of Catholicism, I greatly appreciated this verse because it convinced me I had access to God the Father through Christ. Priests are mediators. With Christ being our Mediator, He also becomes our High Priest:

Hebrews 4:14 We have a great High Priest who has passed through the heavens, Jesus, the Son of God.

Under the Old Covenant, there was an earthly high priest, and under the New Covenant, we have a heavenly High Priest.

Fifth, Unlike the Old Covenant, Under the New Covenant, We Become the Priests, Temple, and Sacrifices

The word priest doesn’t occur in Jeremiah 31:34, but because the verse indirectly makes the point that priests won’t be teachers or mediators any longer, the Jews would understand that God is dissolving the priesthood under the New Covenant. We don’t have a priesthood today, so this doesn’t sound like a big deal to us, but it would’ve sounded like a huge deal to people in the Old Testament and left them with many questions:

“If there is no priesthood, what about the temple? Who’s going to take care of it? What about our sacrifices? Who’s going to perform them?” Under the New Covenant, is there a priesthood, temple, or sacrifices? Yes!

The phrase “from the least of them to the greatest” is God’s way of saying everyone has equal access to Him. Nobody has more access because they are somehow better than others. Because all believers have equal access to God under the New Covenant, we are all identified as priests:

1 Peter 2:5 you yourselves like living stones are being built up as a spiritual house, to be a holy priesthood, to offer spiritual sacrifices acceptable to God through Jesus Christ…. 9 But you are a chosen race, a royal priesthood.

There’s still a temple:

1 Corinthians 3:16 Do you not know that you are the temple of God?

One reason God let the temple be destroyed is He planned for us to become the temple. And there are still sacrifices! Just like we are priests, and just like we are the temple, we are also expected to be sacrifices:

Romans 12:1 I appeal to you therefore, brothers, by the mercies of God, to present your bodies as a living sacrifice.

Under the Old Covenant, God accepted the sacrifices of dead animals as worship. Under the New Covenant, we worship by offering ourselves as living sacrifices; our very lives are lifted up in worship.

Sixth, Unlike the Old Covenant, Under the New Covenant, Sin Is Forgiven

Jeremiah 31:34c For I will forgive their iniquity, and I will remember their sin no more.”

This is the most dramatic contrast between the Old and New Covenants. It’s easy to read this and say, “Didn’t God forgive sin under the Old Covenant?” The answer is, “No.” If He did, Christ wouldn’t have had to die, and a New Covenant wouldn’t have been needed:

Hebrews 10:4 [Under the Old Covenant] it is impossible for the blood of bulls and goats to take away sins.

So you say, “If animal sacrifices didn’t forgive or take away sins, what was their purpose?” The word atone means cover. Sacrifices under the Old Covenant atoned for, or covered sin, until it could be forgiven through Christ’s sacrifice.

The Old Covenant required continually sacrificing animals. Consider this: Through the centuries, an ocean of blood was shed to temporarily cover sin so people could approach God. All those Old Testament sacrifices prefigured the once-for-all sacrifice for sins Christ would offer under the New Covenant.

Micah 7:19 [God] will cast all our sins into the depths of the sea.

With Jesus’s death, there is a depthless ocean of forgiveness sufficient for the sins of the whole world. We must confess our sins, repent, and believe that God provided this sacrifice in His Son, Jesus Christ.

Footnotes

1. The word “heart” is the key to the New Covenant because it deals with people’s hearts. The Ten Commandments (the Old Covenant) primarily deal with outward actions: not murdering, lying, stealing, or committing adultery. But when Jesus preached the Sermon on the Mount, He focused on the inward: Don’t be angry or lustful. Jesus was looking to internal observance of the Law, obeying in the heart, and it’s prophesied of here. ↩︎
2. Also, 2 Corinthians 3:7 says, ” Now if the ministry of death, carved in letters on stone, came with such glory that the Israelites could not gaze at Moses’ face because of its glory, which was being brought to an end. ↩︎
3. The Old Testament frequently discussed writing God’s commands, or law, on our hearts. Here are a few examples:
   
   -Deuteronomy 11:18 You shall therefore lay up these words of mine in your heart and in your soul.
   -Proverbs 3:3 Let not steadfast love and faithfulness forsake you; bind them around your neck; write them on the tablet of your heart.
   -Proverbs 6:21 Bind [My commands] on your heart always.
   -Proverbs 7:3 Write [my commands on the tablet of your heart.
   
   This is what God wanted His people to do in the Old Testament.
   In Jeremiah 31:33, God said, “I will put my law within them, and I will write it on their hearts.” These Old Testament verses almost tell us what God wanted to do with the New Covenant. God is so gracious that when He recognized we wouldn’t do this, He said He would do it for us under the New Covenant. ↩︎