Hebrews 7:21Meaning & Commentary from the Church Fathers

The Apostle points out two advantages of the New Testament priesthood. It has no end, unlike the priesthood under the law, and it was established with an oath. He proves all this from the person of Christ, who received this priesthood. He says, "according to the power of an endless life." He also proves it by the oath, because God "swore," and by the fact itself. For that law, he says, has been annulled because it was weak, while this one stands because it has power.

He says that the priests of the law are appointed without an oath. God swore concerning none of them, saying, "You shall be a priest according to the law." But Christ is appointed with an oath given through God, who says to Him: You are a priest according to a new manner, not according to Aaron, but according to Melchizedek.

In the tribe of Levi, since priests were appointed without an oath, they also did not remain forever. But He, Christ, remains Priest unto the ages of ages, since it was impossible for the oath to prove false. Of it was said: "The Lord has sworn and will not repent: You are the Presbyter of presbyters forever, according to the order of Melchizedek."

Since God Himself appointed the priests under the law, and after their cessation appointed another in their place, the Apostle had to say that God appointed the former without an oath. But in appointing this One, He added an oath. Therefore do not think that this priesthood too will cease, like the former one, and that another will again replace it. Such a supposition is rejected by the oath that was given.

"For they became priests without an oath," that is, the priests under the law. "But this One with an oath" means Christ. "Through Him who said to Him: The Lord has sworn and will not repent: You are a priest according to the order of Melchizedek" (Ps 109:4). "With an oath" means the oath belonging to God, who speaks to Him through David. "The Lord has sworn" means that He uttered this and what follows in an unchangeable manner, as was explained above.

Third, by the time of the Messiah’s coming, the weakness and uselessness of the former law had become evident in fact. For it brought nothing to perfection.

Therefore human hope of drawing near to God required both a new foundation and a stronger assurance from the Lord God.

This foundation was revealed in the new and better covenant of God with men, of which Jesus became the surety. The assurance was revealed in the oath by which the Lord established this covenant with men and ordered the new and better priesthood.

All this again happened according to the words of Scripture concerning Melchizedek, the Old Testament type of Christ: “The Lord has sworn and will not repent: You are a priest forever, according to the order of Melchizedek.”

In defining the dignity of this new hope, or, as the Apostle later says, covenant, he directs attention to the Minister of this covenant or union.

The Old Testament priests were appointed to their ministry without receiving oath-bound assurance that the priesthood would remain forever in their lineage. But concerning the New Testament High Priest, God swore that He would be High Priest forever.

Therefore Jesus serves a better covenant (cf. 7:19), a more reliable union, and even becomes its surety. That is, He guarantees that the conditions of the covenant will be kept holy by both sides.

Moses and the Old Testament priests could not say this. Jesus guarantees it by the very fact that in Him we already see the conditions of the union fulfilled, both on God’s side and on man’s.