11 Now if perfection had been attainable through the levitical priesthood-for the people received the law under this priesthood-what further need would there have been to speak of another priest arising according to the order of Melchizedek, rather than one according to the order of Aaron? 12 For when there is a change in the priesthood, there is necessarily a change in the law as well. 13 Now the one of whom these things are spoken belonged to another tribe, from which no one has ever served at the altar. 14 For it is evident that our Lord was descended from Judah, and in connection with that tribe Moses said nothing about priests. 15 It is even more obvious when another priest arises, resembling Melchizedek, 16 one who has become a priest, not through a legal requirement concerning physical descent, but through the power of an indestructible life. 17 For it is attested of him, "You are a priest forever, according to the order of Melchizedek."
Matthew Henry's Commentary on Hebrews 7:11-17
Commentary on Hebrews 7:11-25
(Read Hebrews 7:11-25)
The priesthood and law by which perfection could not come, are done away; a Priest is risen, and a dispensation now set up, by which true believers may be made perfect. That there is such a change is plain. The law which made the Levitical priesthood, showed that the priests were frail, dying creatures, not able to save their own lives, much less could they save the souls of those who came to them. But the High Priest of our profession holds his office by the power of endless life in himself; not only to keep himself alive, but to give spiritual and eternal life to all who rely upon his sacrifice and intercession. The better covenant, of which Jesus was the Surety, is not here contrasted with the covenant of works, by which every transgressor is shut up under the curse. It is distinguished from the Sinai covenant with Israel, and the legal dispensation under which the church so long remained. The better covenant brought the church and every believer into clearer light, more perfect liberty, and more abundant privileges. In the order of Aaron there was a multitude of priests, of high priests one after another; but in the priesthood of Christ there is only one and the same. This is the believer's safety and happiness, that this everlasting High Priest is able to save to the uttermost, in all times, in all cases. Surely then it becomes us to desire a spirituality and holiness, as much beyond those of the Old Testament believers, as our advantages exceed theirs.