The nature of Christ’s atonement is primarily grounded in his obedience. We can say that the whole of Christ’s work as second and last Adam in making atonement is that he was perfectly obedient to the Father where the first Adam was not. We see this often in Scripture but particularly in John’s Gospel:
For this reason the Father loves me, because I lay down my life that I may take it up again. No one takes it from me, but I lay it down of my own accord. I have authority to lay it down, and I have authority to take it up again. This charge I have received from my Father. (John 10:17-18)Here we see that Christ’s work in providing atonement for his people was that he obeyed the charge given to him by the Father. This is out of obedience and exercising his authority in the way that the Father directs. This appears elsewhere as Jesus says that he came down from heaven not to do his own will but the will of the Father who sent him (John 6:38). Isaiah’s prophecies of the Messiah’s atoning death treat him first of all as the servant of the Lord (Is. 52-53). In announcing the fulfillment of this prophecy Paul says that Jesus, though being God, took the form of a servant (Phil. 2:7-8; Gal. 4:4). In his epistle to the church in Rome Paul writes that it is through the obedience of Christ that the many are made righteous (Rom. 5:19).
Typically we make a distinction between the active and passive obedience of Christ. This is to say that there are two distinct aspects of Christ’s obedience. Here we should make two clarifying points. When we talk about Christ’s passive obedience we do not in anyway mean that Christ was involuntarily subjected to the violence of crucifixion. That would go against the very idea of obedience in the things that he suffered. Second, we must avoid the mistake of saying that Christ’s righteous life was his active obedience and his sufferings and death were his passive obedience. Active and passive obedience are not a distinction between periods of his life.
The true purpose of this distinction is to say that God’s law has both penal sanctions and positive demands. So we see that holiness before God demands both perfect obedience to God’s law as we see that keeping the law means keeping the law at every point (James 2:10) and that God’s law demands punishment whenever there is a violation. So Christ’s active obedience consists in that he perfectly obeyed the law of God and was without sin while his passive obedience consists in that he perfectly suffered all of the penalties for our violation of God’s law. Thus Paul writes that Jesus became sin for us (passive obedience) that we might become the righteousness of God in him (active obedience) (1 Cor. 5:21). This can be seen in the letter to the Hebrews.
In the days of his flesh, Jesus offered up prayers and supplications, with loud cries and tears, to him who was able to save him from death, and he was heard because of his reverence. Although he was a son, he learned obedience through what he suffered. And being made perfect, he became the source of eternal salvation to all who obey him, being designated by God a high priest after the order of Melchizedek. (Heb. 5:7-10)Here we can see several things about Christ’s obedience:
1. It was as the Second Person of the Trinity, as the eternal Son of God, became incarnate that he was perfectly obedient to the Father in the flesh. This is not limited to the fact that he became incarnate but throughout the entire time of his days on earth in the flesh he was perfectly obedient.
2. It was not only through his death that Jesus exercised his perfect obedience but throughout his time on earth and all the things that he suffered including hunger, thirst, beatings, mockings, scourgings, his crucifixion, and even emotional sufferings as he wept after the death of Lazarus. Throughout all of this Christ remained perfectly obedient to the will of the Father.
3. It is through his death on the cross as the supreme act of obedience that Jesus becomes the only source of eternal salvation to all who obey him and therefore place their faith in him and repent of their sins.
4. It is this perfect obedience of Christ that is imputed to his people so that it is as we are in him that we are saved. Christ’s passive obedience is imputed to us so that his sufferings and death on the cross are the satisfaction of our sins and guilt. Christ’s active obedience is imputed to us as God looks at us as righteous in Christ. This shows us that there is nothing else we can do in relation to the law of God. Christ's sacrifice, made 2,000 years ago, perfectly satisfied the penalty for our all our past, present, and future transgressions. His perfect is credited to us so that in the eyes of the law we are declared to be perfectly righteous before the Judge of all.
5. “Obedience, therefore, is not something that may be conceived of artificially or abstractedly. It is obedience that enlisted all the resources of his perfect humanity, obedience that resided in his person, and obedience of which he is ever the perfect embodiment. It is obedience that finds its permanent efficacy and virtue in him. And we become the beneficiaries of it, indeed the partakers of it, by union with him. It is this that serves to advertise the significance of that which is the central truth of all soteriology, namely, union and communion with Christ.” (John Murray, Redemption: Accomplished and Applied, Grand Rapids: William B. Eerdman's, 1955, 24).