Jer 31:31, Heb 7:11-12, Mk 14:24, Jn 19:30

The Old Testament law is not perfect. So God made a new covenant. (Heb 8:7-13, Jer 31:31, Heb 7:11-12)

Heb 8:7 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.

Jer 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:

Heb 7:11 If therefore perfection were by the Levitical priesthood, (for under it the people received the law,) what further need was there that another priest should rise after the order of Melchisedec, and not be called after the order of Aaron? 12 For the priesthood being changed, there is made of necessity a change also of the law.

By shedding his blood on the cross, Jesus fulfilled the work of Christ, the new covenant. (Mk 14:24, Jn 19:30)

Mk 14:24 And he said unto them, This is my blood of the new testament, which is shed for many.

Jn 19:30 When Jesus therefore had received the vinegar, he said, It is finished: and he bowed his head, and gave up the ghost.