Psalms 110:4

4. The perpetuity of the priesthood, here asserted on God's oath, corresponds with that of the kingly office just explained. after the order--(He 7:15) after the similitude of Melchisedek, is fully expounded by Paul, to denote not only perpetuity, appointment of God, and a royal priesthood, but also the absence of priestly descent and succession, and superiority to the Aaronic order.

Robert Jamieson, A. R. Fausset & David Brown, 1871 · public domain

Verse 4 The Lord hath sworn - Has most firmly purposed, and will most certainly perform it, feeling himself bound by his purpose, as an honest man would by his oath. And will not repent - Will never change this purpose; it is perfectly without condition, and without contingency. Nothing is left here to the will of man or angel. Christ shall be incarnated, and the Gospel of his salvation shall be preached over the whole earth. This is an irresistible decree of that God who loves mankind. Thou art a priest for ever - The word כהן cohen signifies, not only a priest, but also a prince; as, in the patriarchal times, most heads of families had and exercised both political and sacerdotal authority over all their descendants. Every priest had a threefold office: 1. He was an instructor of the family or tribe over which he presided. 2. He offered sacrifices for the sins of the people, to reconcile them to God, and give them access to his presence. 3. He was their mediator, and interceded for them. So is Christ, the grand, the universal Instructor, by his word and Spirit; the Lamb of God, who, by his sacrificial offering of himself, takes away the sin of the world, and still continues to exhibit himself before the throne in his sacrificial character; and also the great Mediator between God and man: and in these characters he is a Priest for ever. He will instruct, apply the sacrificial offering, and intercede for man, till time shall be no more. After the order of Melchizedek - For the elucidation of this point, the reader is requested to refer to the notes on Gen 14:18, Gen 14:19, and to the observations at the end of that chapter, where the subject, relative to the person, name, and office of this ancient king, is fully discussed; and it will be necessary to read that note, etc., as if appended to this place. Melchizedek was king of Salem, that is, king of Jerusalem; for Salem was its ancient name: but שלם salem signifies peace, and צדק tsedek, righteousness. Christ is styled the Prince of peace; and he is the king that rules in the empire of righteousness; and all peace and righteousness proceed from him, Heb 7:2. He is priest after the order of Melchizedek - after his pattern; in the same kind or manner of way in which this ancient king was priest. Calmet properly observes that there were three orders of priesthood. 1. That of royalty. All ancient kings being, in virture of their office, priests also. This seems to have been considered as the natural right of royalty, as it obtained in almost every nation of the earth, from the beginning of the world down to the end of the Roman empire. 2. That of the first-born. This right appertained naturally to Reuben, as the first-born in the family of Jacob. 3. That of the Levites, instituted by God himself, and taken from Reuben, because of his transgression. The Levitical priesthood ended with the Jewish polity; and that also of the first-born, which had been absorbed in it. This order, therefore, was not perpetual; it was intended to last only for a time. But that of royalty is perpetual, though not now in general use, because founded in what is called natural right. It is, therefore, according to this most ancient order, that Christ is a Priest for ever. The kings of England as heads of the Church appointing all bishops, continue to assume, in a certain way, this original right. Melchizedek is said to be "without father without mother, without beginning of days, or end of life." We have no account of his parents; nothing of his birth; nothing of his death. Christ, as to his Divine nature, is without father or mother, and without beginning of days; nor can he have any end. Other priests could not continue by reason of death; but he is the Eternal, he cannot die, and therefore can have no successor: "He is a priest For Ever." Therefore, as Melchizedek was a priest and a king, and had no successor, so shall Christ be: of the increase and government of his kingdom there shall be no end. Melchizedek was priest of the Most High God; and consequently not of one people or nation, but of the universe. Aaron was priest of one people, and for a time only; Jesus is priest of all mankind, and for ever. He tasted death for every man; he is the King eternal; he has the keys of hell and of death. As God is the King and Governor of all human beings, Christ, being the priest of the Most High God, must also be the priest for and over all whom this most high God made and governs; and therefore he is the priest, the atoning sacrifice, of the whole human race. In this the main similitude consists between the order of Melchizedek and that of Christ.

Adam Clarke, 1831 · public domain