In the Letter to the Hebrews, we are introduced to the mystery of how Christ’s sacrificial death works unto the forgiveness of our sins. We learn from the author that Christ’s sacrifice is efficacious because, firstly, it consists of a sacrifice offered by a perfect high priest. It is efficacious, secondly, because this perfect high priest offers his sacrifice in a perfect sanctuary and is the perfect and immediate mediator between God and man. Thirdly, it is efficacious because the perfect high priest offers himself as the perfect victim. These three aspects of Christ’s sacrifice, all of which are made possible by the fact that He is both God and man, give it the power to cause the perfection of those for whom it is offered. It does so by bringing about a new covenant between God and man whereby man is purified from sin and God’s law is written on the hearts of man and sanctifies him.
The first major aspect that makes Christ’s sacrificial death work unto the forgiveness of our sins is the truth that Christ is the perfect high priest. Because He is both God and man, Jesus Christ is able to be the perfect high priest, and this perfect priesthood is one element of what allows him to offer a perfectly efficacious sacrifice. Foundational to Christ’s being our high priest is the fact that He became incarnate. The author of the Letter to the Hebrews explains that Christ became “like his brethren in every respect, so that he might become a merciful and faithful high priest in the service of God, to make expiation for the sins of the people” (2:17). If Christ had not become man, He would not be able to serve as man’s representative. Because Christ did become man, He is able to act on man’s behalf and is able to free man from sin from within. In A Bible Commentary for Teaching and Preaching, Thomas Long writes of this passage, “here we see an image of Christ as the liberator, the one who breaks into the slave quarters and sets the slaves free.” Long is expressing the truth that Christ is able to set us free from the power of sin precisely through His humanity. It is because He has become man and has suffered and undergone temptation that Christ is able to “help those who are tempted” (2:17) and is able to “sympathize with our weaknesses” (4:15).
At the same time, it is only because Christ is God that He is actually able to be our perfect high priest. As God, Christ is completely free from sin and so is not enslaved by the many imperfections by which man is enslaved (4:15). As Long explains, “Jesus, like the old priests, was fully human, but unlike them his humanity did not erode into despair, loss of faith, and sin.” Thus, we see that Christ was like the old priests in all of their good aspects, but unlike the old priests in all of their imperfections. Because Christ is God, He is able to not only sympathize with us but to also be “victorious over temptations.” Through this victory, He is able to “give his brothers the grace and help needed to triumph as he did.” Thus, we come to understand that Christ is able to be our high priest through His humanity, and that He is able to be our perfect high priest through His divinity.
The second major aspect that makes Christ’s sacrifice work unto the forgiveness of our sins is that Christ’s priestly sanctuary is heaven itself. The priests of the Old Covenant were mediators between man and God; they offered sacrifices in the earthly sanctuary on behalf of the Israelite people, and also mediated the presence of God to the people. Long explains this twofold mediation of priesthood by stating that the priest of the Old Covenant “faces in two directions. On behalf of the people, He faces toward God and travels to the holy place with their offerings. . . the priest also faces toward humanity on behalf of God. The priest represents God’s holy presence among the people.” Thus, the main task of the priests of the Old Covenant was to act as a channel between God and man. Like the priests of the Old Covenant, Jesus Christ acts as a mediator between God and man.
Unlike the priests of the Old Covenant, however, Jesus Christ is the perfect mediator because He is God Himself and His sanctuary, therefore, is heaven itself. In the Old Covenant, the high priest alone could enter the inner room of the sanctuary, and only once a year (9:7). As the divine high priest, however, Jesus is able to go as “a forerunner on our behalf” to the “shrine behind the curtain” (6:19-20). Through His sacrificial death, Christ opened the veil which separated man from the presence of God and opened the sanctuary of heaven. For this reason, Jesus Christ, the Second Person of the Trinity who reigns at the right hand of the Father as both God and man, is able to make recourse for us to the Father immediately and continuously, and His priesthood lasts forever and ever (7:23, 9:24). While in the Old Covenant the high priest alone was allowed to enter into the sanctuary, in the New Covenant Christ makes it possible for all men to follow Him into the sanctuary—only in this case it is no earthly sanctuary, but a heavenly sanctuary where man can see God face to face.
The third major aspect that gives efficacy to Christ’s sacrifice is the fact that, as the perfect high priest, Jesus Christ offered the perfect victim in expiation for our sins—Himself. Because He is man, Jesus Christ is able to offer Himself as a victim for the sacrifice. Because the victim of this sacrifice is perfect, the sacrifice itself is perfect, and there is no need for it to be repeated. The author of the Letter to the Hebrews tells us that “under the law, almost everything is purified with blood, and without the shedding of blood there is no forgiveness of sins” (9:22). Through His incarnation, Christ has a human body and human blood. In His sacrifice, Christ, the perfect high priest, did not offer the blood of animals, but His very own blood, and in doing so He secured forgiveness of sins and “an eternal redemption” (9:12). Because He is God, Jesus Christ is the most spotless victim possible for the sacrifice. His sacrifice actually has infinite merit because it is offered in God’s infinite charity. He alone is “holy, blameless, unstained, separated from sinners, exalted above the heavens” (7:26). Christ’s sacrifice is not just perfectly good but infinitely good because Christ himself is infinitely good, and he sacrifices himself! Therefore, His sacrifice once offered was enough to take away the sins of man for all eternity. As the author of Hebrews writes, Jesus Christ “has no need, like those high priests, to offer sacrifices daily, first for his own sins and then for those of the people; he did this once and for all when he offered up himself” (7:27). Thus, we see once again that the unity of Christ’s divine and human natures allow Him to take away our sins––for the unity of His natures allows Him to be not only perfect priest but also perfect victim.
Through Christ’s perfect sacrifice, man’s sins are forgiven and man is cleansed from within. The sacrifices of the Old Law were imperfect and left man guilty, but through Christ’s death, a New Covenant is established whereby man’s guilt is really and truly taken away. In the sacrifices of the Old Covenant, the priests offered their sacrifices to God on behalf of the Israelite people, but these sacrifices were imperfect and did not have the power to truly cleanse the people of their sins. They did not make perfect “those who draw near” (10:1), but rather brought about external cleansings “for the purification of the flesh” from ritual impurities (9:13). As Long writes, if the sacrifices of the Old Law “were effective to cleanse people from sin and to make them perfect in the sight of God, then they would not come back year after year and offer the same sacrifices.” As imperfect as these purifications were, the fact that the blood of animals did, in fact, have the power to purify flesh, serves as an important foundation for understanding just how powerful the blood of Christ Himself must be. Unlike the blood of animals, which cleansed man externally, the blood of Christ cleanses man from sin internally. If the blood of animals had the power to cleanse the flesh, the author of Hebrews writes, “how much more shall the blood of Christ, who through the eternal Spirit offered himself without blemish to God, purify your conscience from dead works to serve the living God” (9:14). In this verse, we see that Christ’s sacrifice allows for perfect and complete cleansing from sin. It has the very power to purify our consciences and to transform us in such a way that we are able to “serve the living God” (9:14).
Thus, it is clear that what makes Christ’s sacrifice on the cross efficacious is that He is the perfect high priest, that He carries out his priesthood as the perfect mediator in the perfect sanctuary, and that He offers Himself as the perfect victim. Because Christ is both God and man, He is able to be a perfect high priest who sympathizes with our weaknesses and yet is more powerful than sin. Likewise, as God and man Christ is able to be present in the sanctuary of heaven rather than an earthly sanctuary, making constant recourse to God the Father on our behalf, and is able to bring God perfectly to man by Himself being God incarnate. Further, because Christ is God and man, He is also able to offer Himself as the perfect victim. His humanity allows Him to shed His blood for the forgiveness of sins, and His divinity makes Him the most perfect offering possible. These three elements of Christ’s one sacrifice together allow Him to be the mediator of a New Covenant which cleanses man from within and writes God’s law on men’s hearts.