"The Christology and soteriology of Hebrews can be summarized in this way. Jesus is the Son of God, a high priest according to the order of Melchizedek. As the Son of God, he is greater than the angels. But in order to rescue humanity from the fear of death and deal effectively with sin, it was necessary for the Son to share in the flesh and blood of humans so that he could become a merciful and faithful high priest. According to Heb 7:21, God appointed him high priest by an oath: "The Lord has sworn and will not change his mind, 'You are a priest forever.'" As a priest according to the order of Melchizedek, Jesus enjoys a superior priesthood that he exercised in a unique way through his death. By dying, he entered the holy of holies, the heavenly sanctuary, where he offered his blood—his very life—for the sins of his brothers and sisters once and for all. In Hebrews, then, Christology and soteriology are intimately related in the person of Jesus, who is both priest and victim."
Frank J. Matera, "The Theology of the Epistle to the Hebrews," in Reading the Epistle to the Hebrews: A Resource for Students, ed. Eric F. Mason and Kevin B. McCruden (Atlanta: Society of Biblical Literature, 2011), 198