The new covenant is a special promise that God made through Jesus Christ to rescue people from the effects of sin. It replaces and completes the old covenant, which was based on the laws God gave to Moses. The Bible mainly talks about this new covenant in the New Testament
The idea of a new covenant is found in several places in the Old Testament (Ezekiel 34:23–31; 37:24–28; Joel 2:12–32). The actual phrase occurs only once (Jeremiah 31:31–34).
In this passage, Jeremiah describes how God's new covenant would be different from the old covenant he made with Moses. The main difference is where God would put his laws. In the old covenant, God wrote his laws on stone tablets (Exodus 31:18; 34:27–32; Deuteronomy 4:13; 5:22; 9:11; 10:3–4). It was also written in a book (Exodus 24:7; compare the phrase “the old way of the written code,” Romans 7:6).
But in the new covenant, God would write his laws directly in people's hearts. This would help people understand more clearly what God wants. People would be able to actually do what God asks (see Romans 8:2–4). Other prophets also talked about how God would work inside people's hearts (Ezekiel 11:19–21; 36:26–27). The prophet Joel said that one day God would give his Spirit to all kinds of people: “I will pour out My Spirit in those days” (Joel 2:28–32).
Another difference is how God’s people know him under the two covenants. Israel knew God under the old covenant. God had revealed himself to Israel, but sometimes they forgot him (Judges 2:10; Hosea 4:1, 6). The prophets wrote that the new covenant would be different: each person would be able to know God personally.
Lastly, the two covenants differ in how God deals with people's sin. Jeremiah said God would forgive his people's bad actions and remove their sins. The people of Israel already knew that God was merciful and forgiving (Exodus 34:6–7). But now Jeremiah was telling them something new: God would never think about their sins again (Jeremiah 31:34). Under the old covenant, people were reminded of their sins every year (Hebrews 10:3). But under the new covenant, God removes all memory of sin (10:14).
A New Covenant
The term “new covenant” appears at least six times in the New Testament (1 Corinthians 11:25; 2 Corinthians 3:6; Hebrews 8:8, 13; 9:15; 12:24) According to some manuscripts, it is likely Luke 22:20, also uses the phrase. In some Greek handwritten copies of Matthew 26:28 and Mark 14:24, the word “new” was added to “blood of the covenant.” These scribes likely added this based on other stories of the Lord’s Supper in 1 Corinthians or possibly in the Gospel of Luke.
Since the word “new” was not in the best Greek copies of the Gospel of Matthew and the Gospel of Mark, it likely was not in the original writings. It is clear from all four stories that Jesus saw the Lord’s Supper as starting a different and therefore “new” covenant. Jesus's death made this new agreement with God official. This was similar to how God had made his first agreement official when Moses offered animal sacrifices (Exodus 24:6–8).
The cup in the Lord’s Supper stands for the blood of Jesus's sacrifice, sealing the new covenant God has made with his people. The church remembers this new covenant, made firm by Jesus's death, each time it celebrates the Lord’s Supper.
When Jesus started the Lord’s Supper, he did not explain what was “new” about the covenant. In other places, he spoke about “baptism with the Holy Spirit” (Acts 1:5; 11:16; compare. Matthew 3:11; Mark 1:8; Luke 3:16; and John 1:33). In the Gospel of John, John the Baptist makes the promise (compare 1 Corinthian 12:13). Both Old Testament predictions refer to the same new covenant that God would make in the future, as shown in 2 Corinthians 3:6. There, Paul stated that God “has qualified us as ministers of a new covenant” (compare. Jeremiah 31:31), not “of the letter but of the Spirit” (compare Joel 2:28–32), for “the letter kills, but the Spirit gives life.”
Why Is the New Covenant Better?
In 2 Corinthians 3, Paul explains the difference between the old and new covenants. The old covenant, which God gave through Moses (3:14), was written on stone and brought death (3:7). But the new covenant that Jesus started is different and better (3:8–9). In this new covenant, God's Spirit writes his laws directly on people's hearts (3:3).
The book of Hebrews in the New Testament explains the new covenant more completely than any other book in the Bible. Hebrews 8:8–12 quotes Jeremiah 31:31–34, which is the longest Old Testament quotation found in the New Testament. In Hebrews 12:24, a different Greek word for “new” is used, but the meaning is the same.
The new covenant is one of the main topics in Hebrews. The book was written to help Christians who were having doubts about their faith. It shows them why their new faith in Jesus was better than their old Jewish beliefs and practices.
The book of Hebrews explains several ways that the new covenant is better than the old covenant, which was no longer needed.
The new covenant has a better priesthood. In the old covenant, priests would serve God's people by speaking to God for them. But these priests were human and would eventually die, so new priests were always needed to replace them (Hebrews 7:23).
The new covenant is different. Jesus is our priest, and he lives forever. He never needs to be replaced, and he is always there to speak to God for his people (7:24–25).
Jesus is a better priest than the priests of the old covenant. The old priests had to offer animal sacrifices again and again. They had to make these sacrifices first for their own sins because they too were sinful people. Then they would make sacrifices for everyone else's sins.
But Jesus was different. He never sinned, so he did not need to make sacrifices for himself. And instead of making many sacrifices, he gave his own life as one final sacrifice that would work forever (7:27; 9:25–28; 10:12).
The new covenant has a better sacrifice. In the old covenant, priests had to kill animals as sacrifices for sin. But these animal sacrifices could only partly cover people's sins, and they had to be repeated over and over (10:2–3).
Jesus's sacrifice was different. When he gave his life, it was one perfect sacrifice that worked completely and forever (9:11–14; 10:1–10).
The new covenant is built on “better promises” than the old (8:6).
The old covenant was not complete and had weaknesses (8:7). This is why it was replaced by something better (8:13). But the new covenant is complete and perfect, and it will last forever (13:20).
The old and new covenants are different in how people can approach God. Under the old covenant, people could not come to God directly. They needed priests to go to God for them (9:6–8). Under the new covenant, everyone can come to God directly. When we do this, God cleanses our hearts and takes away our guilt (compare 9:14 with 9:9).
The new covenant has a better guarantee, a promise made by God himself (7:20–22).
In the new covenant, God promises that his Holy Spirit will live in everyone who believes in Jesus. God gives his Spirit to all his people (6:4). Paul tells us that the Holy Spirit is proof ("seal") that we belong to God and a promise ("pledge") that we will receive everything God has promised us (see 2 Corinthians 1:22; 5:5; Ephesians 1:13–14).
Conclusion
The new covenant completes what God started in the old covenant. It also comes with a new command to love others God puts his laws inside people's hearts through his Holy Spirit. God's Spirit lives in believers and gives them the power to follow his new command (Romans 8:2–4; Galatians 5:16–25). This power from God's Spirit is one of the most important differences between the old and new covenants. The Spirit helps believers do what God asks of them.