Hebrews 7:23-28 occurs in the middle of a larger argument about Jesus being a heavenly high priest.
This is one of the central ideas of Hebrews, and it is a unique contribution in the New Testament to our understanding of Jesus. Our passage has two main points: 1) Because Jesus is not subject to death, in contrast to the earthly priests, as the heavenly high priest he is able to serve and offer salvation perpetually; 2) Jesus only had to sacrifice himself once for all people, in contrast to the repeated sacrifices made by the earthly priests.
Christ is first identified as high priest in Hebrews 2:17, and the basic points are summarized in 4:14-16. The detailed discussion of the designation occupies 5:1-10 and chapters 7-10. In the argument of Hebrews, Christ's identity as the heavenly high priest is what enables him to offer eternal salvation -- so it is a point of tremendous importance! A basic understanding of the argument will provide valuable context for understanding our passage.
The argument is complex, but it may be summarized as follows: Priests in Judaism must be from the tribe of Levi, but as the Messiah, Jesus is from the tribe of Judah (David's tribe). Thus Jesus could not be in the traditional Jewish priesthood. However, Psalm 110, a psalm recognized as a messianic prophecy in the Judaism of the time, contains the line, "You are a priest forever, according to the order of Melchizedek" (verse 4). Melchizedek is an obscure character from the story of Abraham (Genesis 14:17-20), a "priest of God Most High." Psalm 110:4 thus provides a way for Jesus as the Messiah to be a priest, indeed a priest "forever." This last point becomes the basis for the contrast between the eternal priesthood of Jesus and the limited priesthood of the earthly priests.
This contrast is the subject of verses 23-25 in our passage. Earthly priests obviously die, so their priesthood is of limited duration (verse 23), but because of his resurrection and exaltation to God's right hand, Jesus' priesthood will have no end (verse 24). This eternal status thus provides a different order of salvation than that available through the traditional priesthood -- the salvation offered by Jesus is eternal, because his intercession on our behalf will never cease (verse 25). A similar point can be seen in Romans 8:34.
Verses 26-28 provide further contrasts between Jesus and the earthly high priests. While verse 26's adjectives "holy," "blameless," and "undefiled" can be used in a variety of contexts, together with the following phrase, "separated from sinners," they emphasize Jesus' sinlessness, a point made elsewhere in Hebrews (4:15) and by other New Testament writers (e.g. 2 Corinthians 5:21; 1 Peter 2:22; 1 John 3:5).
Other parts of Hebrews emphasize Jesus' identity with us as humans, that he experienced weakness and suffering just as we do (see 2:5-18 and 4:14-16, included in the lectionary texts prior to this week). Here the emphasis is on Jesus' uniqueness, because the point is to contrast Jesus with the earthly priests. This uniqueness is hammered home in the last phrase of verse 26, "exalted above the heavens." It is this exaltation that enables Jesus to be the eternal, heavenly high priest, offering eternal salvation through his eternal intercession.
Verse 27 adds the contrast between the once-for-all nature of Christ's sacrifice and the perpetually repeated sacrifices offered by the earthly priests. This contrast will be greatly elaborated in chapters 9 and 10, especially 10:1-14. The fact that the earthly sacrifices have to be performed repeatedly points to the fact that they cannot take away sins in the first place; otherwise they would cease (10:1-4, 11).
These sacrifices cleanse only "the flesh" (9:13), being unable to "perfect the conscience of the worshiper" (9:9). Christ's sacrifice, on the other hand, was "a single sacrifice for sins" "offered for all time" (10:12), penetrating into our innermost being, cleansing our conscience (9:14), having "perfected for all time those who are sanctified" (10:14). The resulting covenant is thus one of the inside, of the heart and mind, as attested by the Holy Spirit (10:15-16), with the result that other sacrifices are needed no more (10:18).
Verse 28 adds yet two more contrasts between Jesus and the earthly priests. First, the weakness of the earthly high priests contrasts with the perfection of Jesus. The language of Jesus having "been made perfect" often surprises readers. It is not a claim, however, about the intrinsic character of Jesus -- after all, Jesus' sinlessness is a key assertion of Hebrews, as discussed above -- but about his having been fitted perfectly to his role.
In 2:15-18 this perfecting includes his becoming human so that he could properly identify with those he was saving (so also 5:8-9). The context in chapter 7, however, suggests more his exalted status -- he could not fulfill his high priestly role without having been exalted to God's right hand. Thus the perfecting of Jesus as pictured throughout Hebrews includes his incarnation, death, resurrection, and ascension -- the whole story!
The second contrast is that Jesus was appointed high priest with an oath, unlike the earthly priests. This point was explained in 6:13-20 and 7:20-22. The reference is to the aforementioned Psalm 110:4, which precedes the appointment as high priest in the order of Melchizedek with an oath formula, "The Lord has sworn and will not change his mind." The author of Hebrews sees this formula as underscoring the eternal nature of Christ's priesthood.
This is by no means an easy passage -- like most of Hebrews! This is all the more so because the comparison between Jesus and the earthly high priests will not likely strike modern readers or hearers as being of pressing concern. While of major interest in the first century, most Christians today do not think much about the nature of the priesthood. Amidst this comparison, however, the author makes some very important statements about how Jesus accomplished human salvation. The passage is thus well worth the attention of preacher and hearer alike!