Jer 32:37-14, Heb 8:6-13, Heb 10:12-18
In the Old Testament, God promised to establish a new covenant with the people of Israel. Through the new covenant, God's law will be written on the hearts of the people of Israel, and the people of Israel will become God's people. (Jeremiah 31:31-34, Jeremiah 32:37-44)
Jeremiah 31:31 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: 32 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: 33 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. 34 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.
Jeremiah 32:37 Behold, I will gather them out of all countries, whither I have driven them in mine anger, and in my fury, and in great wrath; and I will bring them again unto this place, and I will cause them to dwell safely: 38 And they shall be my people, and I will be their God: 39 And I will give them one heart, and one way, that they may fear me for ever, for the good of them, and of their children after them: 40 And I will make an everlasting covenant with them, that I will not turn away from them, to do them good; but I will put my fear in their hearts, that they shall not depart from me. 41 Yea, I will rejoice over them to do them good, and I will plant them in this land assuredly with my whole heart and with my whole soul. 42 For thus saith the Lord; Like as I have brought all this great evil upon this people, so will I bring upon them all the good that I have promised them. 43 And fields shall be bought in this land, whereof ye say, It is desolate without man or beast; it is given into the hand of the Chaldeans. 44 Men shall buy fields for money, and subscribe evidences, and seal them, and take witnesses in the land of Benjamin, and in the places about Jerusalem, and in the cities of Judah, and in the cities of the mountains, and in the cities of the valley, and in the cities of the south: for I will cause their captivity to return, saith the Lord.
The new covenant that God established is not like the Old Testament law. Through the new covenant, God's law is written on the hearts of the people of Israel, and the people of Israel come to know God. (Hebrews 8:6-13)
Hebrews 8:6 But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises. 7 For if that first covenant had been faultless, then should no place have been sought for the second. 8 For finding fault with them, he saith, Behold, the days come, saith the Lord, when I will make a new covenant with the house of Israel and with the house of Judah: 9 Not according to the covenant that I made with their fathers in the day when I took them by the hand to lead them out of the land of Egypt; because they continued not in my covenant, and I regarded them not, saith the Lord. 10 For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people: 11 And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest. 12 For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more. 13 In that he saith, A new covenant, he hath made the first old. Now that which decayeth and waxeth old is ready to vanish away.
Christ is the new covenant of God who made us eternally perfect by dying as a sacrifice to God for our sins. (Hebrews 10:12-18)
Hebrews 10:12 But this man, after he had offered one sacrifice for sins for ever, sat down on the right hand of God; 13 From henceforth expecting till his enemies be made his footstool. 14 For by one offering he hath perfected for ever them that are sanctified. 15 Whereof the Holy Ghost also is a witness to us: for after that he had said before, 16 This is the covenant that I will make with them after those days, saith the Lord, I will put my laws into their hearts, and in their minds will I write them; 17 And their sins and iniquities will I remember no more. 18 Now where remission of these is, there is no more offering for sin.