The new covenant is spoken about first in the book of Jeremiah. The old covenant that God had established with His people required obedience to the Old Testament Mosaic law. Because the wages of sin is death (Romans 6:23), the law required that people perform rituals and sacrifices in order to please God and remain in His grace. The prophet Jeremiah predicted that there would be a time when God would make a new covenant with the nation of Israel.
“‘The day will come,’ says the Lord, ‘when I will make a new covenant with the people of Israel and Judah. . . . But this is the new covenant I will make with the people of Israel on that day,’ says the Lord. ‘I will put my law in their minds, and I will write them on their hearts. I will be their God, and they will be my people'” (Jeremiah 31:31, 33). Jesus Christ came to fulfill the law of Moses (Matthew 5:17) and create a new covenant between God and His people. The old covenant was written in stone, but the new covenant is written on our hearts, made possible only by faith in Christ, who shed His own blood to atone for the sins of the world. Luke 22:20 says, “After supper, [Jesus] took another cup of wine and said, ‘This wine is the token of God’s new covenant to save you – an agreement sealed with the blood I will pour out for you.'”
Now that we are under the new covenant, we are not under the penalty of the law. We are now given the opportunity to receive salvation as a free gift (Ephesians 2:8-9). Through the life-giving Holy Spirit who lives in all believers (Romans 8:9-11), we can now share in the inheritance of Christ and enjoy a permanent, unbroken relationship with God. Hebrews 9:15 declares, “For this reason Christ is the mediator of a new covenant, that those who are called may receive the promised eternal inheritance—now that He has died as a ransom to set them free from the sins committed under the first covenant.”