15 And it is yet far more evident if, in the likeness of Melchizedek, there arises another priest 16 who has come, not according to the law of a fleshly commandment, but according to the power of an endless life. 17 For He testifies: “You are a priest forever According to the order of Melchizedek.”
And it [change of economy] is yet far more evident
Further proof of the change to the superiority of Christ’s priesthood is that His priesthood will last forever (He 7:17). It was not a temporary system based on type but on the reality which the type illustrated and predicted.
if [since], in the likeness of Melchizedek, there arises another [different kind] priest [Christ]
Jesus’ priesthood was in the order of Melchizedek which was without termination. What Melchizedek was symbolically Jesus is in truth. Jesus’ priesthood was of an entirely different kind that the Levitical.
who [Jesus] has come,
Christ received His priesthood according to the order of Melchizedek.
not according to the law of a fleshly [physical] commandment,
This phrase alludes to the biological descent of the Levitical priesthood. The Old Testament had regulations that a priest could only be one by succession from Levi. Jesus did not come based on the legal requirement about His ancestry. He did not rest His priesthood on genealogy.
The difference between the Levitical priesthood and Christ is the principle upon which His priesthood was established. His priesthood was established based on the power inherent in His life (Ps 110:4). He is a priest “forever.” Only Jesus could match the prophesy of that Psalm.
according to the power [effectiveness] of an endless life.
Jesus killed death through His resurrection (1 Co 15:55; Co 2:12). His priesthood is “forever” and His life indestructible (Ps 110:4; He 7:16, 17). Our Lord inherently possessed eternal life, a life that will never be annulled or abrogated. The Levitical priesthood was only temporary. Jesus was not made a priest by legislation but by an imperishable life. His priesthood cannot perish.
The “for” shows the implication of Jesus “endless” priesthood (He 7:16).
He [Jehovah] testifies:
This is a quote from Psalm 110:4.
“You are a priest forever According to the order of Melchizedek.”
The priesthood of Christ is forever. Nothing can dissolve it. God established His priesthood by an oath in this Psalm (He 7:20).
Because Christ has eternal life He can perfectly intercede on our behalf.
Jesus quoted Psalm 110:4 as referring to Himself in Psalm 110:1 (Mt 22:41-46). His priesthood was eternal and could never be superseded.
Jesus can do what the Levitical priesthood could not do. The latter priesthood rested on the law and genealogy. Jesus’ priesthood rested on His indissoluble life, His eternal life. He takes us into God’s very presence. He anchors us there for eternity (He 6:19). This is a priesthood enabled by an inner “power.”
Jesus ever lives to make intercession for us (He 4:16; 7:24-25).