Christ, the Sublime High Priest

Old and New Covenant Continuity and Fulfillment in Priesthood and Liturgy in Aquinas’s Commentary on Hebrews

Aquinas’s Commentary on Hebrews exquisitely treats of the relationship between the salvific works of Old Covenant sacrifices and their fulfillment in the person of Christ as supreme High Priest of the New Covenant. Contrary to the position of post-reformation interlocutors, Aquinas argues that there exists an organic continuity between Old Covenant high priesthoods and Christ’s. According to Aquinas, Christ’s priesthood holds unrivaled superiority to that of Aaron, precisely because of the truly salvific value of Christ’s Sacrifice, which establishes a perfect, everlasting Covenant that allows man to obtain eternal life. The problem here is: do Christ’s Covenant and Priesthood eradicate past covenant priesthoods?

This essay presents Aquinas’s answer to this by demonstrating Christ’s sublime High Priesthood as perfecting those of the Old Covenant. To that end we will examine, firstly, that Aquinas’s exposition of the humanity of Christ is cardinal to the economy of salvation in his High Priesthood. Secondly, that he draws a continuous relationship between the Old Priesthoods of Aaron and Melchizedek and Christ’s sublime High Priesthood. Thirdly, that Christ’s New Covenant High Priesthood perfectly fulfills all four conditions that the Old Covenant required of a priest. And, lastly, that Christ’s Sacrifice as High Priest has supremacy and preponderance over Aaron’s and Melchizedek’s. This is because Christ’s Sacrifice alone carries the causal effect of everlasting and unbreakable Covenant communion with God for all man.

The Humanity of Christ

“It is precisely because human beings were first created in his image that [Christ] the Son possesses those attributes that authorize him to re-create human beings in his image, and he does so in becoming human himself.”1 Aquinas begins his treatise on Christ’s high priesthood by expositing on Christ’s humanity. This might seem an odd place to begin if we are to explore the divine eternity of his priesthood. Yet, to Aquinas, it is not only Christ’s divinity that renders him capable of instituting a new covenant; it is primarily his humanity that is cardinal to his High Priesthood and his work of salvation.

In the commentary, Aquinas goes to great lengths to illustrate how Christ, while ever possessing the beatific vision, grew in “knowledge gained by experience,” through obediential suffering as man. He repeats this theme throughout the section. As God the Son who possesses all righteousness, he can effectively purge away all sin with great ease. Nonetheless, Christ’s salvific work is primarily accomplished through his humanity, for it was as man and out of love for man that Jesus purged sin; and he does so by the offering of his very self, his own humanity to the Father, as a loving sacrifice for our sin.”2 Aquinas argues that the very purpose of this was so that Christ might stand in a position of true compassion for, and Priestly Lordship over, man’s fallen condition. Fr. Thomas Lane elaborates on this by stating:

Hebrews 2:17 tells us the purpose of Christ’s assimilation of the human condition was that he might have two qualities, mercy (toward us) and trustworthiness (to his Father). The first quality, mercy, is never associated in the Old Testament with the Levitical priests. Christ’s second quality . . . often translated as “faithful,” denoting that Christ was faithful to the mission given him by his Father, could also be translated as “trustworthy” or “worthy of trust.” The latter has the advantage of emphasizing Christ’s ongoing relationship with his Father rather than a onetime act of fidelity in the past, which suits Christ’s role in [Heb 8:1-2], where he sits at the right hand of the Father conducting a liturgy in the heavenly sanctuary.3

At crux here is this reality: God, in his divine nature, is impassible. The God of the universe cannot experience change in his essence. Suffering necessitates change and susceptibility to passion. So when we say “God the Son suffered in his Passion,” it was not in his Divine Nature. Passion only belongs to his Divine Nature by his assumption of the passible human nature.4 Through obediential suffering, Christ becomes the exemplar Covenant High Priest. He supremely transcends all High Priests of the Old Covenant. In him alone is found perfect obedience in human suffering, and, “being made perfect, he became the source of eternal salvation to all who obey him” (Hebrews 5:9). Aquinas asserts: this learning of obedience was through suffering, and what the incarnate Son learned through his obediential suffering was a genuine compassion for us, his fellow man, who were enslaved by the bondage of sin and death.

This was a compassion that he literally did not possess as God prior to the Incarnation. As God alone, the Son is entirely impassible. Only in taking upon himself “our sin-scarred humanity, could Christ be tempted as we are and so become for us [so compassionate a] high priest.”5 In becoming incarnate, suffering is not merely an allusion, it is actual. It is no longer extraneous, it is experienced, it is no longer foreign, it is felt. And it is not avoided, it is embraced. Compassion through suffering is something Christ now literally possesses in a fully human manner.6 Aquinas doesn’t gently gloss over this either. For him, as for Paul, this is one of the pivotal mysteries that renders Christ as our perfect High Priest. “Christ accepted our weakness voluntarily; consequently, [Paul] says that ‘he learned obedience.’”

How difficult it is to obey. Even for the best of us, obedience is often given when it is least painful. Yet Jesus obeyed in the most difficult matters, even to death on the cross (Phil 2:8). He demonstrates how difficult the good of obedience is. Those who have not experienced obedience and have not learned it in difficult matters believe that obedience is very easy. But, in order to know what obedience is, one must learn to obey in difficult matters, and one who has not learned to subject himself by obeying does not know how to rule others well.7 The fact is, Christ would have known by simple recognition what obedience is. Nevertheless, Aquinas and Paul state that he learned obedience from the things he suffered: from difficult things, by suffering and dying. This is so that “by the obedience of one, many shall be made just” (Rom 5:19).8

Taking one step back, then, we see it isn’t merely that Christ’s humanity was necessary for our salvation in his being our High Priest. On a grander scale, Aquinas recognizes that, without obediently suffering, “Christ could not ‘learn’ how to rule as our King and Lord.”9 If our King and Lord is obedient, he can hold us to obedience. If our King and Lord is altogether perfect, he could also perfect us; “for it is the nature of a perfect thing to be able to engender its like.”10 Christ accomplishes this through holding us to the filial obedience of faith. Precisely because he himself did so. Because of this, Aquinas holds, in no uncertain terms, that “it is the Son of God as man, and not as God, who was appointed High Priest by his Father.”11

Continuity in Old and New Priesthoods

From there, Aquinas shows us how both the High Priesthoods of Aaron and Melchizedek foreshadow the High Priesthood of Christ. To both Paul and Aquinas, Christ fulfills the former two High Priesthoods in an exceedingly preeminent way, via his perfect sacrifice on the Cross, which merited his glorious resurrection as eternal High Priest. In fact, the very heart of Aquinas’s Commentary on Hebrews 7-10 demonstrates that Christ’s priesthood and its salvific effects fulfil, and so, are superior to the Old Testament priesthood and its effects. Yet, as Thomas Weinandy reminds us, “the hermeneutical key to this interpretation . . . is one of prefigurement and fulfilment.”12 This is because

. . . the great respect of Hebrews for the Levitical priesthood is clearly evident. Every high priest does not take the honor of high priesthood on himself but is appointed by God (Heb 5:1,4). This is remarkable in that the position of high priest was such that one was in effect born into that position, since it was passed from father to the eldest son… Hebrews wants us to understand that this was God’s plan and those who received the office of high priest in this way did so because they were in fact called by God (Heb 5:4).13

The superiority of the High Priesthood of Jesus is contingent upon the fact that he alone was chosen by God to offer a sacrifice that was perfect in nature, i.e. his sacrificial death on the Cross. It is precisely this that merits his resurrection as the glorious eternal High Priest [for all mankind].”14 In doing so, Christ makes of himself both priest and sacrifice, minister and offering. This act, of fulfilling the Old Testament liturgy, in no way means that Christ eradicates it. Instead, Aquinas does not want to disparage their earthly and material importance. The “sacraments of the Old Law,” as he calls them, while substantially inferior to Christ’s New and Eternal Covenant sacrifice, still “naturally end to a likeness of superior things.”15

In Christ, God elevates the sensible into the spiritual, the transient into the transformative, the natural into the supernatural, and the temporal into the eternal. Because of this, the New and eternal Covenant of Christ “completes and perfects the Old” in a supereminent way, because Christ now mediates a better covenant by which “we are made partakers of the divine nature.”16 This was a feat impossible for the Aaronic and Melchizedekian priesthoods. The Angelic Doctor further distinguishes that the key difference between the Old and New Covenants is that of “fear” and “love.”17 In the Old Covenant, sin was never eradicated. It continued to reign, infecting human nature with its sting, inciting a legitimate fear of death. In Christ, however, man could stand upon the promise of Jeremiah 31. God, benevolent Father that He is, instituted, through Christ, in man a living interior knowledge of the law. God has inscribed his covenant upon our hearts. Through the indwelling of the Holy Spirit, man’s will is now compelled to act upon God’s law.18

Thus, instead of touting the eradication of the Old Covenant, Aquinas points out that the Old Covenant actually prepared man across millenia for the new covenant in Christ. Thus, whatever grace that flows from it is not contained in itself. Old Covenant liturgies and sacrifices were not, by themselves, salvific. Only insofar as they find their fulfillment Christ’s covenant could they be even remotely salvific.19 To this end, Aquinas illustrates how the Old Covenant Tabernacle/tent prefigures both the Church, and heavenly glory. “Inasmuch as it signifies the Old Testament, [the tabernacle] is a figure of a figure; but inasmuch as it signifies future glory, it is a figure of truth in regard to each.”20 Going deeper, he writes that “the holy of holies” of the Tabernacle signified the New Testament, for through it, man is able to come into a foretaste of heavenly glory.21 In like manner, when looking at Melchizedek and Aaron, Aquinas asserts that they both prefigure Christ’s priesthood, albeit in different manners. Christ, like the Aaronic priests, will offer a sacrifice, as is fitting of a High Priest. And like Melchizedek, his priesthood is forever.22 His New does not eradicate the Old. It fulfills it.

Aquinas testifies to this as the firmness of truth: “everything foretold in the Old Law has been fulfilled: (Pr. 12:19) ‘The lip of truth shall be steadfast for ever;’ ‘Not one dot or one iota of the law shall pass away until all be fulfilled’ (Mt. 5:18); ‘The words that proceed from the mouth [of the Lord], [He] will not make void’ (Ps. 88:35). Therefore, it was made valid, because it was not made void.”23 For Aquinas and Paul, Christ is the glorious incarnate Son. Christ is superior to the angels and to Moses. Yet, this same Christ by his obediential suffering, is the Great High Priest, superior to Melchizedek and Aaron and their priestly descendants. He alone perfects their sacrifice. He alone elevates their priesthood. In Christ, the Old is not eradicated, it is elevated. It isn’t discarded, it is divinized. It isn’t forgotten. It is fulfilled.24 Christ alone perfectly meets all that the Old demanded, and he sublimates it to the level of the supernatural.

Christ Fulfills the Old Testament

Following from that, Aquinas emphasizes how Christ Priesthood perfectly fulfills all four conditions that the Old Covenant required of a priest: that the priest must be holy, innocent, unstained by sin and separated from sinners. From Hebrews, Aquinas picks up this reality: Christ isn’t merely instituting his own priesthood devoid of the past. He is, in fact, showing himself to be the true and perfect high priest that all the Old Laws were anticipating. For Aquinas, there is no cutoff in salvation history, only continuity. So Aquinas sets down the four qualities from the epistle that were required of Old Covenant priests. First, that he is holy: Christ evidently had this perfectly. Holiness in Sacred Scripture implies purity consecrated to God.25 Christ had no need to make atonement for himself. Christ had no need to be set apart for God. He is, as Lk. 1:35 states, “the Holy Son of God.”

Secondly, the priest should be innocent: For Aquinas, innocence is purity toward one’s neighbor; borrowing from Psalm 23:4, “The innocent in hands, and clean of heart: is he who has not taken his soul in vain, nor sworn deceitfully to his neighbor.” Christ was completely innocent. Not only was he without sin, in fact, Christ alone could say absolutely: “I have walked in my innocence” (Ps. 25:11).

Thirdly, that he be unstained by past sin, in particular regard to himself: Here, Aquinas hearkens to Lev. 21:17: “Whosoever of our seed through their families has a blemish, he shall not offer bread to his God.” The one who is to minister eternal atonement cannot himself be in need of atonement. At the same time, the sacrifice he offers must, of itself, be without blemish. Christ proverbially stunned human history when he offered himself as oblation; priest became sacrifice; minister became offering; firstborn became the slaughtered, Lion of Judah became Lamb of God. In fact, of Christ alone can it be rightly said: “[the sacrifice] shall be a lamb without blemish” (Ex. 12:5). Fourthly, the priest must be separated from sinners. Drawing once more from levitical law, Aquinas quotes “[The Priest] shall not mingle the stock of his kindred with the common people of his nation” (Lev. 21:15). In a very real sense, Christ was fully man, ever among man, but forever remaining “perfectly separated from sinners.” Aquinas continues: “And to such a degree He was separated that He was made . . . exalted above the heavens.” Dr. Matthew Levering elaborates on this:

The task of every “high priest chosen from among men” is “to act on behalf of men in relation to God, to offer gifts and sacrifices for sins” (Hebrews 5:1). Jesus performs this task perfectly, in contrast to the limited power of merely human priests. Unlike a merely human high priest, Jesus is “holy, blameless, unstained, separated from sinners, exalted above the heavens” (Hebrews 7:26) . . . When he “made purification for sins” (Hebrews 1:3), Jesus did so as a man who “reflects the glory of God and bears the very stamp of his nature” (Hebrews 1:3). He is both a human high priest and the eternal Son of God.26

Paul writes, “He sits on the right hand of the majesty on high” (Heb. 1:3). Clearly, Christ is more than a sufficiently competent priest, he is the only candidate to perfectly fulfill all the Old Law requirements for a High Priest.27 He was, is, and forever will be sublime High Priest of the New and Eternal Covenant.

Christ’s Perfect Sacrifice

This brings us to Aquinas’s demonstration of the centrality, supremacy, and preponderance of Christ’s Sacrifice as High Priest over those of the Old Covenant. Again, Aquinas asserts that they are not forgotten. However, here he concedes to this reality that Paul himself asserts: “In speaking of a new covenant, [the first is treated as] obsolete. And what is becoming obsolete and growing old is ready to vanish away.”28 For Aquinas, Christ’s Sacrifice alone carries the efficient causal effect of everlasting and unbreakable Covenant communion between God and man. Old covenant sacrifices and liturgies must, of necessity, make way for the New. Inasmuch as every High Priest must offer gifts and Sacrifice (Hebrews 8:3), Christ’s supreme Sacrifice perfectly fulfills all those of the Old Law.

Aquinas describes three of the effects of Christ’s New sacrifice that the Old didn’t possess: Firstly, that Christ’s sacrifice as High Priest brought about man’s perfect union with God. The reason why priesthoods of the Old Testament failed to establish this communion is because, for man to be brought into God’s beatific vision, God’s grace is required. Man’s own power is not capable of this. None of us can make a self-willed, running leap into heaven, try as we might. Therefore, God, benevolent Father that he is, lavishes grace upon us in Christ’s sacrifice, to draw our hearts to Himself. The soul of man is called to respond to this divine initiative of covenant union.29

Secondly, perfect knowledge of God. The most perfect knowledge, for Aquinas, is not acquired, but received. By this, Aquinas posits that Christ’s High Priestly sacrifice brought to our souls infused knowledge of God in two ways: firstly, by the spirit of God infusing wisdom within us, and, secondly, when we come into our heavenly inheritance and we are endowed with the vision of our Father. Then, we will receive wisdom and knowledge unacquired. We will know ourselves and him for eternity, yet never tire in apprehending his wisdom.30

Thirdly, the remission of man’s sins. Here, Aquinas distinguishes between iniquity (one’s offence against one’s neighbor) and sin (an offence against oneself). What Christ’s sacrifice achieves for us is the remission of both iniquity and man’s sin. The priesthoods of the Old Law helped remove iniquity, but what Christ does on the Cross restores much more than communal harmony. Christ’s sacrifice removes guilt and restores harmony within the soul of man, something the Old Covenant sacrifices could never do.31 For Aquinas, when man receives this remission of sin in Christ’s sacrifice, it is binding. God will never waver on this, for “the gift and call of God are without repentance” (Rom 11:29). While both the Old and New Testaments were instituted in order that by them the soul of man might come to God, it is only Christ’s holy, High Priestly sacrifice that effectively achieves this.32 Paul emphasizes this in that “although he was Son, he learned obedience through what he suffered; and being made perfect he became the source of salvation to all who obey him” (Hebrews 5:8-9). Frank Sheed penetrates this mystery deeper in teaching that:

Jesus himself in his manhood, was the beneficiary of his own redeeming sacrifice. Being made perfect, he could now be Head of a new humanity redeemed by him, as Adam had been head of the old race fallen in him. Re-born with Christ, we are united with his divinity, indwelt by Father and Holy Spirit. That is Redemption.33

Hence, Christ’s sacrifice was holy, because his offering was his holy life. He offered himself to the Father, as a sacrifice of man, as man, for man; by God, as God, to God.34 The effect of Jesus’s death is nothing short of redemption from the bondage of sin “by the precious blood of an unspotted lamb” (1 Pt 1:18).”35 “Every high priest is appointed to offer up gifts and sacrifices” (Heb. 5:1); but the sacrifice which Christ offered takes away all sins. This is why his sacrifice could cause so great a final effect: the everlasting and unbreakable communion between God and man. Christ our High Priest is now seated [at the right hand of the Father]; his assumed humanity, our humanity, is now connected, to the godhead.36 Why? Because, by his one offering, he has perfected all man, for all time. By his one offering, he has sanctified us, he has reconciled us and he has united us to God. By His one offering, all man, now has access to God (cf. Rom. 5:12).37 Christ has taken metaphorical hope and made it metaphysical reality.

The Way to Heaven

Aquinas truly does an exemplary job connecting the ministry of Old Covenant priesthood and its fulfillment in Christ. One would be at a loss to express how much he has to teach us of covenant continuity between the Old and the New. To conclude the entire thrust of this essay, allow me to stand on the shoulders of the giant himself:

Therefore, brethren . . . since we have confidence to enter the sanctuary [holies] by the blood of Christ: “In whom we have boldness and access with confidence by the faith of him” (Eph. 3:12): And the blood of Christ . . . is “the blood of the New Testament” (Mt. 26:28), i.e., the new promise of heavenly beatitude . . . because Christ by His blood opened a new and living way for us . . . It is new, because before Christ, no [High Priest] had found it. This, therefore, is the way to go to heaven.38

  1. Thomas Gerard Weinandy, Daniel A. Keating, and John Yocum, eds. Aquinas on Scripture: An Introduction to His Biblical Commentaries (London: A&C Black, 2005), 229.
  2. Weinandy, Keating, and Yocum, Aquinas on Scripture.
  3. Fr. Thomas J. Lane, The Catholic Priesthood: Biblical Foundations (Steubenville, OH: Emmaus Road Publishing, 2016).
  4. ST III. 46. 12. Res.
  5. Weinandy, Keating, and Yocum, Aquinas on Scripture, 233.
  6. Weinandy, Keating, and Yocum, Aquinas on Scripture, 235.
  7. Thomas Aquinas, “Commentary on the Epistle to the Hebrews,” trans. Chrysostom Baer (South Bend: St. Augustine’s, 2006), 5:8–14.
  8. Aquinas, “Commentary on the Epistle to the Hebrews.”
  9. Aquinas, “Commentary on the Epistle to the Hebrews.”
  10. Weinandy, Keating, and Yocum, Aquinas on Scripture, 235.
  11. Weinandy, Keating, and Yocum, Aquinas on Scripture, 234.
  12. Weinandy, Keating, and Yocum, Aquinas on Scripture, 236.
  13. Lane, The Catholic Priesthood.
  14. Weinandy, Keating, and Yocum, Aquinas on Scripture, 236.
  15. Aquinas, “Commentary on the Epistle to the Hebrews,” 8:1–5.
  16. Aquinas, “Commentary on the Epistle to the Hebrews,” 8:6–10b.
  17. Aquinas, “Commentary on the Epistle to the Hebrews,” 8:6–10b; 10:1–18; 12:18–24.
  18. Aquinas, “Commentary on the Epistle to the Hebrews,” 8:6–10b.
  19. Aquinas, “Commentary on the Epistle to the Hebrews,” 239.
  20. Aquinas, “Commentary on the Epistle to the Hebrews,” 9:1–5.
  21. Aquinas, “Commentary on the Epistle to the Hebrews,” 9:1-5.
  22. Weinandy, Keating, and Yocum, Aquinas on Scripture, 236.
  23. Weinandy, Keating, and Yocum, Aquinas on Scripture, 2:1 (94).
  24. Weinandy, Keating, and Yocum, Aquinas on Scripture, 234.
  25. Aquinas, “Commentary on the Epistle to the Hebrews,” 7:20–28 (375).
  26. Matthew Levering, Christ and the Catholic Priesthood: Ecclesial Hierarchy and the Pattern of the Trinity (Chicago: Liturgy Training Publications, 2010), 61.
  27. Aquinas, “Commentary on the Epistle to the Hebrews,” 7:20–28 (375).
  28. Cf. Hebrews 8:13.
  29. Aquinas, “Commentary on the Epistle to the Hebrews,” 8:10b–13 (406).
  30. Aquinas, “Commentary on the Epistle to the Hebrews,” 8:10b–13 (408–410).
  31. Aquinas, “Commentary on the Epistle to the Hebrews,” 8:10b–13 (411–412).
  32. Aquinas, “Commentary on the Epistle to the Hebrews,” 9:1 (414).
  33. Frank J. Sheed, Theology & Sanity (London: A&C Black, 1978).
  34. Aquinas, “Commentary on the Epistle to the Hebrews,” 1:2 (40).
  35. Aquinas, “Commentary on the Epistle to the Hebrews,” 9:4 (448).
  36. Aquinas, “Commentary on the Epistle to the Hebrews,” 8:1 (381).
  37. Aquinas, “Commentary on the Epistle to the Hebrews,” 10:1 (499).
  38. Aquinas, “Commentary on the Epistle to the Hebrews,” 10:2 (502).
Marcus Benedict Peter About Marcus Benedict Peter

Marcus Benedict Peter hails from Malaysia and has been involved in teaching, faith formation, missionary work, and evangelization of the Faith since 2008. He has ministered and spoken in Malaysia, Singapore, the Philippines, India, and the United States. In 2018, he received his MA in Theology at Ave Maria University, Florida. Marcus regularly writes and creates content for his website,, where he does work on Catholic biblical theology, apologetics, and evangelization. At present, Marcus and his bride, Stephanie Mae Peter, live in South Lyon, MI. Marcus teaches Theology at Father Gabriel Richard High School in Ann Arbor, MI.


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