“Therefore, if perfection were through the Levitical priesthood (for under it the people received the law), what further need was there that another priest should rise according to the order of Melchizedek, and not be called according to the order of Aaron? For the priesthood being changed, of necessity there is also a change of the law. For He of whom these things are spoken belongs to another tribe, from which no man has officiated at the altar. For it is evident that our Lord arose from Judah, of which tribe Moses spoke nothing concerning priesthood” (Hebrews 7:11-14).
The Levitical priesthood was to the Law of Moses what a foundation is to a building. If it could not restore full, unfettered access to God, then the Law of Moses was flawed at its foundation. It could not do what God needed and wanted done in the realm of reconciliation.
The Melchizekan priesthood as realized in Jesus could and did do what God needed and wanted done. But, under the Law of Moses, it was illegal and presumptuous. Jesus was the Son of Abraham, Isaac, Jacob, and Judah (not Levi). Therefore, He could not serve as priest under the Law of Moses.
For the perfect priesthood of Jesus to become legally authorized, a change of the law was not optional. It had to be. For it to be legitimate, it also had to fulfill the predictions made of it by Jeremiah (see Hebrews 8:8-12).
The Melchizekan priesthood of Christ is to the new covenant what a foundation is to a building. Like our hope, our law is both sure and steadfast. Its foundation is one-hundred percent pure spiritual bedrock.
