Hebrews 7:24

But this man, because he continueth ever, hath an unchangeable priesthood.

Christ holds a priesthood that never passes to a successor and will never be replaced or superseded, because He Himself continues forever as priest after the order of Melchisedec. This stands in contrast to earthly priests, who were removed by death and could not continue long, so their office passed from one man to another. He ministers this everlasting office in the heavenly sanctuary by the offering of His own blood, as the holy, harmless and undefiled High Priest who needed no daily sacrifice for Himself but made atonement once when He offered up Himself. Because He ever lives He continually intercedes as ascended Saviour, Advocate and Surety, presenting His own merits and bearing His people by almighty power, and so is able to save fully and to the uttermost all who come to God through Him. Through His death and entrance into the heavenly Holy Place He opened a new and living way that removes the separation caused by sin, so guilty, tempted sinners who can do no good thing apart from Him must depend wholly on His grace and merits to draw near to God with full assurance.

Everlasting Unchanging Priesthood

This man has an unchangeable priesthood because He continues forever, and that priesthood never passes to a successor and will never be replaced or superseded, being forever after the order of Melchisedec. In contrast to earthly priests who were removed by death and could not continue long, so that their office passed from man to man, His permanent priesthood never ends because He lives forever. The earthly high priest was designed in a special way to represent Christ, who was to become a high priest forever after the order of Melchisedec, and unlike that corrupt human priesthood that passed from man to man, this order does not pass to another and will not be superseded by another.

The earlier high priests and their services were only types of Him pointing to Him, and when He appeared the need for their service vanished. The sacrifices and priests of the Jewish system pointed to Christ, but apart from Him they could not secure salvation, for Christ alone by His perfect and infinite sacrifice opens the way to God. The human high priests before and at His first advent did not truly represent this enduring priesthood, for they were often corrupt and sought office through ambition, bribery, or violence. Those Jewish high priests at His first advent had not been divinely appointed, in contrast to Christ's enduring priesthood after the order of Melchisedec which lasts forever and will not pass to a successor or be replaced by another priesthood.

Jesus already headed this unchanging priesthood and was the only true high priest and the head of an unchangeable priesthood over the house of God even as a helpless infant of a few weeks brought to the temple. Taken in the priest's arms and enrolled by name in the roll of Israel's firstborn as Mary's son and brother to humanity, He already held that office though the redemption money was paid for Him under the law. He was the Ancient of Days whose goings forth have been from of old, even from everlasting. His enrolled name was the hope of fallen humanity because He Himself would pay the ransom for the sins of the whole world.

After suffering and dying as the sin-bearer of the human race, He entered upon His priestly office permanently and forever as High Priest for the whole world. Because He lives forever His priesthood lasts forever.

Heavenly Mediation and Salvation

He ministers this everlasting priesthood in both apartments of the heavenly sanctuary by the offering of His own blood, just as earthly priests with animal blood ministered in both apartments of the earthly sanctuary. The earthly sanctuary with its two apartments and furniture was a figure of the heavenly, and its sacrifices and offerings and the particulars of its work were given so that looking back to them gives understanding of His work as laying hold of the merits of a Saviour to come. He is the holy, harmless, undefiled High Priest, separate from sinners and higher than the heavens, touched with human infirmities because tempted in all points, who needs no daily sacrifice first for His own sins and then for the people's, for He made atonement once when He offered up Himself.

Because He ever lives He continually intercedes as the ascended Savior, Advocate and Surety, bearing His people by almighty power and presenting them to the Father in infinite love. He presents His own merits as the Conqueror claiming the trophies of victory rather than as a petitioner persuading the Father to compassion, and as the true High Priest He represents humanity in the heavenly courts. His mediatorial work surpasses the typical priesthood in dignity and glory, enabling Him to save fully, completely, and to the uttermost all who come to God through Him. Through Him the separation caused by sin is overcome so that guilty sinners gain access to God.

His death opened a new and living way and He entered the heavenly Holy Place as High Priest for the whole world, removing the division between Jew and Gentile so there is no longer a wall of partition. He is the people's only secure hope, leading those who follow Him toward the light and safety found with God. Tempted human beings, still sinners saved only by His grace and merits, must depend wholly on Him, for apart from Him they can do no good thing, yet through Him they may draw near with full assurance and will be dealt with according to their works.