If we are not careful, we can downplay the humanity of Jesus. We are used to defending the deity of Christ, and rightly so, for the deity of Christ has frequently been attacked in church history. However, a merely divine Jesus could not have saved us. We need a human being to stand in for us, for only a sinless human being can bear the wrath of God in the place of sinful human beings. We dare not lose sight of that fact, which we might if we downplay the humanity of Jesus.
Continuing the presentation of the perfect efficacy of Christ’s atonement, the author of Hebrews argues for the necessity of Jesus’ humanity. Having explained that the blood of bulls and goats cannot take away sin (Heb. 10:4), he builds on that by exploring the key reason why the blood of Jesus provides true atonement, namely, the perfect obedience of Jesus according to His human nature. Hebrews 10:5–7 quotes from Psalm 40:6–8, wherein David explores what the Lord truly wants from us. As we see, David says that God is looking not for animal sacrifices but for people to delight in doing His will.
We must be careful here not to set the sacrifices in opposition to doing the will of God, for the law—an expression of God’s will—did mandate the sacrificial system. David’s ultimate point, rather, is that the sacrifices do no good if they are not accompanied by a penitent heart that seeks to obey the Lord. Scripture frequently uses hyperbole wherein God expresses His displeasure with sacrifices (e.g., Jer. 6:20) to make the point that apart from the right heart attitude, giving offerings and sacrifices is just going through the motions.
Of course, even the best of us cannot muster up the perfect heart attitude or desire for obedience to accompany our worship. The best we can do, by God’s grace, is give sincere but imperfect worship and praise. That is one reason why the old covenant sacrifices were ultimately ineffectual; none of the worshipers could summon the perfect desire for obedience, let alone accomplish the obedience required. But Christ could and did. God prepared a body for Him (Heb. 10:5), and John Owen states that “body” is shorthand for the human nature of our Lord. The Son was sent by the Father to assume our humanity in the power of the Holy Spirit, and in His life and death He obeyed His Father perfectly according to that nature (1 Peter 2:22). Thus, the sacrifice He offered of Himself was offered in the perfect spirit and can accomplish our salvation.