For the priesthood being changed, of necessity there is also a change of the Law. (Hebrews 7:12)
Change The Priesthood
The Law of Moses is no longer binding as law which includes the law’s preamble called the Ten Commandments. It becomes increasingly difficult for Bible students to understand the law of Christ when they fail to clarify divine authority changing from the children of Israel to men of every nation. Part of the confusion occurs when a separation between the Old and New Testament is not put in its proper order. The Lord gave men the Old Testament as the evidence of His divine will but not as a binding law for all men to follow. Like Paul’s argument to the church at Rome, justification did not come through the Law of Moses. Abraham, who did not live according to the Law of Moses, was justified by faith. Moses lived most of his life without the law named after him. He was eighty years old when the law was given to the Hebrews. The Law of Moses was only given to the nation of Israel.
One of the foundations of the Law of Moses was the priesthood. Moses’ brother, Aaron, was the first High Priest of the nation. His sons, Nadab, Abihu, Eleazar, and Ithamar, were the first priests, with Eleazar succeeding his father as High Priest. The Law was stringent that only those from the tribe of Levi could be priests and serve as High Priest. None of the other tribes could serve as priests, including the tribe of Judah. The apostasy of Israel began when after Solomon’s death, the kingdom was divided, and Jeroboam made shrines on the high places and made priests from every class of people who were not of the sons of Levi. This continued until the destruction of the ten tribes by Assyria. The Law of Moses clearly established the true priests could only come from the tribe of Levi.
Jesus was born of the house of David, the tribe of Judah. Matthew and Luke record the genealogy of Jesus, showing the Lord came from the lineage of David. Under the Law of Moses, Jesus could not be a priest nor a High Priest, and yet the book of Hebrews is a thesis on how Jesus of Nazareth, a man from the tribe of Judah, is now the Apostle and High Priest of those who confess Jesus to be the Christ, the Son of the Living God. Jesus was called by God as High Priest not according to the order of Aaron but the order of Melchizedek, High Priest and King of Salem in the days of Abraham. In the Law of Moses, nothing is said that a man from the tribe of Judah could be the High Priest. Under the law, He would sin by taking on the High Priest role because He was not from Aaron’s lineage. David was a king but was not a High Priest. Jesus was from the house of David.
The argument Paul makes in Hebrews is clear that Jesus is the High Priest appointed by God to serve as King and High Priest. Believing that Jesus is the High Priest over the house of God establishes the Law of Moses (including the Ten Commandments) has been done away with, and the Law of Christ is the only binding authority for salvation. And if the priesthood is changed, the Law must also be changed to permit it. There can be no authority for instrumental music, keeping the Sabbath, and imposing the Ten Commandments as the priesthood has changed, nullifying the old Law and its ordinances. Jesus is both King and High Priest, establishing a law apart from the law given to Israel because He came from the tribe of Judah. It is impossible to serve Jesus as Lord and hold to the Law of Moses.