God has a problem, early on, with the first covenant He makes with His people. He finds fault with them, and seeks another way of making His people right with Him. There is no denying there is something wrong with the old covenant, says the writer of Hebrews. (see Hebrews 8:7-8, NIV)
The key here is that God finds fault with His people, and He requires some way to resolve this separation of Himself from the people He has chosen. He cannot abide sin, but His law is not achieving the end He desires. He’s resorted to punishment, to discipline, to promises; but these do not lead His people to love Him consistently enough to turn from their evil ways. As a matter of fact, God knows His people are essentially incapable of turning to Him.
Therefore God looks forward to His new covenant in which He puts His law in the minds of His people. This law is inside; no longer an outside force. Rather this law is written on the hearts of God’s people. God declares:
“No longer does a man teach his neighbor, or a man his brother, saying, ‘Know the Lord,’ because they all know Me, from the least of them to the greatest. For I forgive their wickedness and remember their sins no more.” (Hebrews 8:10-12)
Yet, someone may argue that Jesus states emphatically that not a letter of the law is set aside. Since Jesus Himself fulfills every requirement of God’s law, no contradiction exists. The law is external for us; but for God’s Son, the law is always internal. Hence Jesus meets all God’s expectations for the people of God. Jesus gives us His own righteousness like a robe we wear on the outside while the Holy Spirit transforms us on the inside. Kind of like dressing for the cold while the glow of warmth rises inside.