Melchisedec was king of righteousness and king of peace. The new millennial order will be a throne upon which One will sit who is both King and Priest.
He had no beginning and He will have no end. His priesthood and throne are eternal.
His having received tithes of Abraham, who was father of Levi, shows who was the greater.
Israel's priests, who have died, received tithes, but this Priest liveth forever.
Thus the priesthood and all of the order formed around it have been replaced by a new order.
Like Melchisedec, this Priest had no pedigree. He sprang from Judah and came not by carnal commandment but after the power of endless life.
Therefore, there is the setting aside of the commandment and the bringing in of a better hope by which we draw nigh to God.
Since this Man has an unchangeable priesthood, He can save to the uttermost all who come to God by Him, "seeing He ever liveth to make intercession for them."
He who is made High Priest by an oath became us, who is holy, harmless, undefiled, separate from sinners, and made higher than the heavens. This High Priest is God's Son, consecrated forevermore.
Hebrews 8
We have such an High Priest in heaven, a "minister of the sanctuary, and of the true tabernacle, which the Lord pitched."
If Priest, He must have something to offer. He offered Himself.
The pattern given to Moses on the mount was typical of heavenly things. This is the tabernacle, not the temple which prefigures earthly glory.
The calling for a better covenant must of necessity void the old. The new will be written in the mind and heart. It will also include an inherent knowledge of God. The old must vanish away.
God will be merciful to Israel's unrighteousness, and their sins and iniquities will He remember no more.