The Unrepealable Word: Christ's Forever Priesthood Text: Psalm 110:4
Introduction: The World's Revolving Priesthoods
We live in a world of frantic, anxious activity. Modern man is desperately trying to find a way to mediate between his guilty conscience and the silence of the universe he has created for himself. He knows, deep down, that he is unclean, that he is not right, and that he needs someone or something to stand in the gap for him. And so, he invents priesthoods. He manufactures them on an industrial scale. These are not priesthoods of robes and incense, but they are priesthoods nonetheless, demanding total allegiance and promising a flimsy, temporary salvation.
The secular state offers a political priesthood. It says, "Elect us, give us your money and your children, and we will absolve you of your social guilt. We will build a utopia where your sins of privilege and inequality are washed away by legislation and bureaucracy." The therapeutic culture offers a psychological priesthood. It says, "Come to us, pay our fees, confess your traumas, and we will mediate a peace treaty with your inner self. Your guilt is not sin; it is a maladjustment." The cult of progress offers a technological priesthood. It says, "Trust in the algorithm, have faith in the next innovation, and we will deliver you from the weaknesses of your flesh into a transhumanist paradise."
Each of these modern priesthoods is a flimsy sham. They are all temporary, they are all man-made, and they are all based on a lie. They are Aaronic priesthoods on their last legs, constantly needing to be replaced, constantly failing, because they are administered by dying men who must first offer sacrifices for their own pathetic sins. They offer a salvation that can be revoked, a peace that can be disturbed, and a righteousness that is as filthy as the rags they wear. They are, in short, a great cosmic shuffling of deck chairs on a sinking ship.
Into this chaos of failing mediators and revocable promises, Psalm 110:4 speaks a word of absolute, bedrock finality. It is a word from God the Father to God the Son, spoken in the hearing of David, establishing a new and eternal order. It is a divine oath, a sworn and settled decree that establishes a priesthood that does not fail, cannot be replaced, and will never be repealed. This verse is the foundation of our eternal security, because our security does not rest in our grip on Him, but in the unchangeable word of the Father who appointed Him as our priest forever.
The Text
Yahweh has sworn and will not change His mind,
“You are a priest forever
According to the order of Melchizedek.”
(Psalm 110:4 LSB)
The Divine Oath (v. 4a)
The verse begins with the most solemn declaration possible:
"Yahweh has sworn and will not change His mind..." (Psalm 110:4a)
We must stop and feel the weight of this. In our day, words are cheap. Promises are disposable. Oaths are treated as mere formalities, to be broken when they become inconvenient. But when God swears an oath, He is doing something of immense significance. An oath is a form of self-malediction. The one swearing the oath is essentially saying, "If I fail to do what I am promising, may the curses of this covenant fall upon my own head."
Now, for a man to swear an oath, he must swear by something greater than himself, which is why we traditionally swear on a Bible or say, "so help me God." As the book of Hebrews tells us, "For men indeed swear by the greater, and an oath for confirmation is for them an end of all dispute" (Hebrews 6:16). But when God swears an oath, what is greater than Himself by which He can swear? There is nothing. And so, as Hebrews goes on to say, "He swore by Himself" (Hebrews 6:13). God puts His own divine character, His own eternal being, on the line. He is pledging the entirety of who He is to the fulfillment of this promise. This is the ultimate guarantee. It is the gold standard of reality.
And notice the second clause: "and will not change His mind." The Hebrew here means He will not repent, He will not relent, He will not regret this decision. This is not a temporary policy. This is not a trial run. This is a permanent, irreversible, eternal decree. The Father has looked upon the Son and has, with a divine oath that makes the foundations of the mountains tremble, established Him in His office. This is crucial because the Aaronic priesthood, the Levitical system, was designed to be temporary. God always intended to replace it. It was a placeholder, a shadow. But this priesthood, the one established by this oath, is final. There will be no other. There is no plan B. The entire stability of the cosmos and the security of our salvation rests upon the fact that God does not change His mind about this.
The Eternal Office (v. 4b)
The content of the oath is then declared:
"You are a priest forever..." (Psalm 110:4b)
The "You" here is the one David calls "my Lord" in verse one, the Messiah, the Lord Jesus Christ. And the office He is given is that of a priest. A priest does two things primarily: he represents God to the people, and he represents the people to God. He offers sacrifice for sin and he makes intercession. The Levitical priests did this day after day, year after year, offering the blood of bulls and goats, which could never truly take away sin (Hebrews 10:4). They were mortal men, and their work was never finished. When they died, another priest had to take their place. Their ministry was a constant reminder of sin, a revolving door of temporary atonement.
But Christ's priesthood is "forever." This single word demolishes the entire temporary structure of the old covenant sacrificial system. Because Christ is eternal, His priesthood is eternal. Because He offered Himself once for all, His sacrifice is eternally effective (Hebrews 7:27). Because He ever lives to make intercession for us, our access to the Father is perpetually secure (Hebrews 7:25). He does not need a successor because He never dies. His work is not repetitive because it was perfect and complete. This is why, when He finished His work, He sat down at the right hand of the Father. The Levitical priests never sat down; their work was never done. Christ sat down because His was.
This is the bedrock of our assurance. Our salvation is not a precarious thing that we have to maintain through our own priestly efforts. We do not have to keep offering sacrifices for our daily sins. We have a permanent priest, a permanent sacrifice, and therefore, a permanent salvation. To doubt this is to question the effectiveness of His work and the truthfulness of the Father's oath.
The Superior Order (v. 4c)
Finally, the nature of this priesthood is defined by its pattern:
"According to the order of Melchizedek." (Psalm 110:4c)
Who is this mysterious figure, Melchizedek? He appears briefly in Genesis 14, is mentioned here in Psalm 110, and then the author of Hebrews unpacks his significance for seven chapters. He was the king of Salem (which means peace) and a priest of the Most High God. His name means "king of righteousness." So he is a king of righteousness and a king of peace. He meets Abraham returning from battle, brings out bread and wine, and blesses him. And Abraham, the great patriarch, gives him a tenth of all the spoils.
The author of Hebrews argues that this makes Melchizedek's priesthood superior to Aaron's. How? First, Abraham paid tithes to him. And since Levi was still in the loins of his great-grandfather Abraham, the Levitical priesthood, in a sense, paid tithes to Melchizedek. The lesser pays tithes to the greater. Second, Melchizedek blessed Abraham. And "beyond all contradiction the lesser is blessed by the better" (Hebrews 7:7). So this priesthood is greater than the one that would come through Abraham's descendants.
But there is more. Melchizedek's priesthood is of a different kind. It is a royal priesthood. He is both king and priest. Under the Mosaic law, these two offices were strictly separated. Saul was rejected for unlawfully intruding on the priest's office, and Uzziah was struck with leprosy for the same. But Christ unites these two offices in His person perfectly. He is our King who rules and defends us, and He is our Priest who sacrifices and intercedes for us. He has the authority of a king and the compassion of a priest.
Furthermore, Melchizedek appears in the Genesis narrative without any recorded genealogy, without a recorded birth or death. He is "without father, without mother, without genealogy, having neither beginning of days nor end of life" (Hebrews 7:3). The text of Scripture presents him this way to make him a type, a pattern, of the Son of God, whose priesthood is not based on lineage or earthly descent, but on the power of an indestructible life. Christ's priesthood is not something He inherited; it is what He is, eternally. This is a superior order, a heavenly order, not an earthly one.
Our Unshakeable Hope
So what does this mean for us, here and now, surrounded by the failing priesthoods of our age? It means everything. It means our standing before God is not based on our performance, our political activism, our psychological health, or our technological savvy. Our standing before God is based entirely on the finished work of our great High Priest, Jesus Christ.
When you sin, when you fail, when your conscience accuses you, where do you run? Do you run to the political priests who tell you to offset your guilt with public virtue signaling? Do you run to the therapeutic priests who tell you to forgive yourself? Or do you run to the throne of grace, where your eternal High Priest stands ready to apply the benefits of His one, perfect, sufficient sacrifice to you?
The Father has sworn an oath. He will not change His mind. Your priest is forever. This is not a temporary appointment. He cannot be voted out of office. He cannot be impeached. He will not retire. He will not die. Therefore, your salvation is secure. Your forgiveness is final. Your access to God is guaranteed. This is not because you are so good at holding on, but because He is so good at His job, a job to which He was appointed by an unrepealable, divine oath.
Therefore, we can have a robust and confident faith. We are not like the adherents of these modern, secular priesthoods, who are always anxious, always striving, always needing the next new program to assure them of their rightness. Their mediators are frauds. Our Mediator is the Son of God. Their systems are sinking sand. Our hope is built on the unchangeable Word of God, sworn in an oath by God Himself. He is our priest, forever, according to the order of Melchizedek. And that is the final word.