Matthew 5:17 Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil. 18 For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.
The thing is this, Jesus fulfilled the Law.
He was the only one who could.
He gave his sinless life in sacrifice to redeem us from the condemnation of the Law.
Not only so, but the New Covenant was ratified by his blood.
The Law was part of the Covenant which God made with Israel at Sinai.
Israel failed to keep the Covenant, so God promised a New Covenant.
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.
The writer to the Hebrews explains:
Hebrews 8:8 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.
The New Covenant replaces the Old Covenant
Hebrews 8:13 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.
Jesus Christ is the mediator of the New Covenant
Hebrews 12:24 And to Jesus the mediator of the new covenant, and to the blood of sprinkling, that speaketh better things than that of Abel.
The Law cannot save, because no one other than Jesus Christ could keep it.
Romans 3:20 Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.
The Law served to convict everyone of sin and condemn them to death.
Jesus Christ is the Messiah promised by God who can redeem us from sin and death.
The Law given through Moses is replaced by the commandments of Jesus Christ.
John 15:13 Greater love hath no man than this, that a man lay down his life for his friends. 14 Ye are my friends, if ye do whatsoever I command you.
Salvation from the time of Adam onwards has always been by faith, not by keeping the Law.
Faith in the promise of God to provide a redeemer.
One who would redeem us from the curse of the Law.
Galatians 2:16 Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
Galatians 3:10 For as many as are of the works of the law are under the curse: for it is written, Cursed is every one that continueth not in all things which are written in the book of the law to do them. 11 But that no man is justified by the law in the sight of God, it is evident: for, The just shall live by faith. 12 And the law is not of faith: but, The man that doeth them shall live in them. 13 Christ hath redeemed us from the curse of the law, being made a curse for us: for it is written, Cursed is every one that hangeth on a tree: 14 That the blessing of Abraham might come on the Gentiles through Jesus Christ; that we might receive the promise of the Spirit through faith. 15 Brethren, I speak after the manner of men; Though it be but a man’s covenant, yet if it be confirmed, no man disannulleth, or addeth thereto. 16 Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ. 17 And this I say, that the covenant, that was confirmed before of God in Christ, the law, which was four hundred and thirty years after, cannot disannul, that it should make the promise of none effect. 18 For if the inheritance be of the law, it is no more of promise: but God gave it to Abraham by promise.
19 Wherefore then serveth the law? It was added because of transgressions, till the seed should come to whom the promise was made; and it was ordained by angels in the hand of a mediator. 20 Now a mediator is not a mediator of one, but God is one. 21 Is the law then against the promises of God? God forbid: for if there had been a law given which could have given life, verily righteousness should have been by the law. 22 But the scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe. 23 But before faith came, we were kept under the law, shut up unto the faith which should afterwards be revealed. 24 Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith. 25 But after that faith is come, we are no longer under a schoolmaster. 26 For ye are all the children of God by faith in Christ Jesus. 27 For as many of you as have been baptized into Christ have put on Christ. 28 There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus. 29 And if ye be Christ’s, then are ye Abraham’s seed, and heirs according to the promise.
Those who believe and obey the gospel become heirs of the promise made to Abraham some 400 years before the Law was given.
There is a lot more written in the New Testament (really the New Covenant) to show that the Law of Moses is no longer in force, having been replaced by the Law of Christ.
The council at Jerusalem concluded:
Acts 15:24 Forasmuch as we have heard, that certain which went out from us have troubled you with words, subverting your souls, saying, Ye must be circumcised, and keep the law: to whom we gave no such commandment: 25 It seemed good unto us, being assembled with one accord, to send chosen men unto you with our beloved Barnabas and Paul, 26 Men that have hazarded their lives for the name of our Lord Jesus Christ. 27 We have sent therefore Judas and Silas, who shall also tell you the same things by mouth. 28 For it seemed good to the Holy Spirit, and to us, to lay upon you no greater burden than these necessary things; 29 That ye abstain from meats offered to idols, and from blood, and from things strangled, and from fornication: from which if ye keep yourselves, ye shall do well. Fare ye well.
I hope this helps,