Matthew 5:17-20 - to Fulfill the Law
Christ came to fulfill the Law?
Answer: The Law of Moses paved the way for the perfect Law: the "Law of Christ" (Gal. 6:2).
To avoid misunderstanding about this:
Galatians 6:2: "Bear one another’s burdens, and thereby fulfill the law of Christ" (emphasis added).
God gave the Old Law to the Israelites many centuries before the birth of Christ (Deu. 5:1-5). However, this law was never intended to be permanent; it was formally completed upon Christ's death on the Cross.
Some may find this unpalatable, but it is a biblical truth. When Christ cried out from the Cross, "It is finished!" (Matt. 27:50-51), the veil of the Temple was torn in two. What did this mean?
Well, because the "veil of the Temple" was a barrier between God and Man, there could never be any direct contact between the two. The veil excluded everyone (but the high priest, and he only once a year) from the Presence of God in the Holy of holies.
[ Note: Throughout the patriarchal period, many men offered sacrifices to God: Abel, Noah, Abraham, Job, etc., because the male head of the household was often considered its "priest", one allowed to do so prior to Moses and the Law.]
Christ's death changed that. He tore the veil from top to bottom, allowing us to speak to God through Him, as our High Priest. He is now our path to God the Father, allowing us "in Christ" to pray and have our prayers heard (and answered) by the Almighty without a physical high priest — and without bloody, carnal sacrifices (that typify the consequences of sin).
Christ abrogated the Old Covenant by fulfilling it (Matt. 5:17) with the New Covenant (and, indeed, a much more demanding one at that). Thus, He made the Old "obsolete":
Hebrews 8:13: "When He said, 'A new covenant,' He has made the first obsolete. But whatever is becoming obsolete and growing old is ready to disappear."
If we accept that words have meaning, then Christ's sacrifice "plērōsai" — fulfilled, or completed, or supplanted, or superseded the Law of Moses, pure and simple. The Law of Moses was sustained by the Aaronic Priesthood. Many passages affirm the end of this "Levitical priesthood" (as with the torn veil of the Temple) and of the Mosaic regime.
The Law of Moses was nailed to the Cross with Christ at death (Col. 2:14). In the apostle Paul's letter to the Romans, he wrote:
Romans 7:4, 6: "Therefore, my brethren, you also were made to die to the Law through the body of Christ, so that you might be joined to another, to Him who was raised from the dead...
6But now we have been released from the Law [of Moses], having died to that by which we were bound, so that we serve in newness of the Spirit [of Christ] and not in oldness of the letter [of the Law]" (emphasis added).
We are discharged from the Old Law, its having been superseded by the "Royal Law" in Christ (Jas. 2:8). That is, we have been set free from the entire O/T Law including its priesthood and sacrificial system.
Some may insist that this change was minor, where only the ceremonial or ministerial aspects were completed. However, this is not what the Letter to the Hebrews has to say:
Hebrews 7:11-12: "Now if perfection was through the Levitical priesthood (for on the basis of it the people received the Law), what further need was there for another priest to arise according to the order of Melchizedek, and not be designated according to the order of Aaron? For when the priesthood is changed, of necessity there takes place a change of law also" (emphasis added).
However we decide to translate this passage, there can be little doubt that the Mosaic order was reinstituted in a more perfect form upon the inauguration of the new priesthood, one in which all saints partake as priests and saints (cf. 1 Pet. 2:9, temples: 1 Cor. 6:19). And, this occurs through the new Law of Christ, also known as the Law of Liberty (Jas. 1:25, 2:12).
No matter how one decides to parse the Greek: plērōsai, the Law of Moses was fulfilled, or completed, or supplanted, or superseded by Christ.
Addendum
Matthew 5:17-20: "Do not think that I came to abolish the Law or the Prophets; I did not come to abolish but to fulfill. 18For truly I say to you, until heaven and earth pass away, not the smallest letter or stroke shall pass from the Law until all is accomplished.
19Whoever then annuls one of the least of these commandments, and teaches others to do the same, shall be called least in the kingdom of heaven; but whoever keeps and teaches them, he shall be called great in the kingdom of heaven. 20For I say to you that unless your righteousness surpasses that of the scribes and Pharisees, you will not enter the kingdom of heaven."
As stated above, Israel had held the Law of Moses in the greatest esteem, just as it should have been. Naturally, anyone suggesting otherwise would be met with contempt. Nonetheless, as God, Christ was very deliberate in His announcements early in His ministry of His relationship to the Law of Moses. He would thus fulfill the Law in every respect when, upon His death, He "paid off the debt" by completing it.
How did He fulfill the Law?: 1) By His perfect obedience; 2) By his manifestation as the Messiah; 3) By extending His teaching, thus lifting His Law (Law of Christ) to new heights — thus, superseding Old Testament teachings with His "perfect Law", and 4) nailing the Law of Moses to the Cross (Col. 2:14).
The New Testament would be fulfilled (cf. Lk. 24:44); it was "written for our example" (1 Cor. 10:11) as well as for our learning (Rom. 15:4). It is the perfection of the Law of Moses through elevation of its principles, whose changes in Christ are beyond anything previously known by the Law and the Prophets (O/T).
All previous bloody sacrifices were retroactively fulfilled back to Adam and Eve at Christ's death. The Covenant of circumcision was replaced by a "circumcision not made with hands" (Col. 2:11), and so on.
Verse 19 above demonstrates that Christ is now pronouncing the obligations everyone would have under His Law (i.e. not the Law of Moses), which is admittedly not obvious in the passage. Nonetheless, Christ elevated His Own commandments as supreme and that not even the least of them was to be disobeyed: "not the smallest letter or stroke" (5:18).
Beginning at verse 21, Christ then repeatedly announces: "You have heard it said…" followed by "But I [now] tell you…" Christ is fulfilling the Law while at the same time declaring that a new law is about to supersede the old one at His death.
The rest of the N/T, inspired by the Holy Spirit, would complete all of the New Law, thus supplanting the Old Covenant with the New one.