📖 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.

https://youtu.be/04ZpwaZQnHI

Table of contentsLasting Change Must Begin with the HeartThe Heart’s ImportanceThe Old Covenant Didn’t Change the HeartThe Old Covenant Reveals Our SinfulnessThe Most Important Verses in the Old TestamentSix Ways the New Covenant Is Not Like the Old CovenantUnlike the Old Covenant, Under the New Covenant, God Does the WorkSecond, Unlike the Old Covenant, Under the New Covenant, the Focus Is InwardThird, Unlike the Old Covenant, Under the New Covenant, the Holy Spirit Teaches UsFourth, Unlike the Old Covenant, Under the New Covenant, Christ is the Only MediatorFifth, Unlike the Old Covenant, Under the New Covenant, We Become the Priests, Temple, and SacrificesSixth, Unlike the Old Covenant, Under the New Covenant, Sin Is ForgivenFootnotes

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.