One of the most profound truths of the gospel, is that Christ not only took the penalty of our law-breaking, but he also fulfilled the law on our behalf during his life on this earth.
Christ himself said as much in Matthew 3:15, that he came to “fulfill all righteousness”. Christ said this just before he was baptized. John the baptist, rightfully noticed that Jesus didn’t have to be baptized, because he was perfectly righteous. Yet, Jesus didn’t do it for himself — he did it to fulfill a righteousness that we did not have. Paul also expounds on this fact. He says in Galatians 4:4 that Jesus came at God’s predetermined time, and he was “born of a woman, [and] born under the law“. This is a profound verse. As God the Son, Jesus was the very revelation of the law. His very character helped shape the very giving of the Mosaic Law. As such, this means that Jesus was not forcibly subject to the Mosaic Law, as humans are. Mankind is part of God’s creation, being created in his image; and therefore we are held accountable to reflect his character and righteousness through obedience to him. However, Jesus is already the very radiance of the Father (Heb 1:3), being the second person of the Trinity, and therefore already contains the righteousness demanded in the law. So Jesus never had to submit to the law. Instead, Jesus willingly, voluntarily, humbly, subjected himself in the incarnation to full obedience to the Law.
And Jesus didn’t do it for no reason, or for show. Jesus subjected himself to the Law, in order that he might “redeem those who were under the law” (Gal 4:5). In other words, Jesus came to fulfill the law’s demands on behalf of sinful men, that they might be counted righteous. He took the full weight of the burden of the commandments, not for himself, but for us. And all that we might be delivered from the curse of the law (Gal 3:10-14). Jesus was perfectly obedient, as a disciple of the law, that we might be counted as righteous disciples of the law. As Paul says later in 2 Corinthians 5:21, that we might become “the righteousness of God” in him.
Martin Luther says of Galatians 4,
Christ, a divine and human person, begotten of God without beginning and born of the virgin at the appointed time, came not to make a law, but to feel and suffer the extreme terrors of the law and to overcome it, so that he might completely abolish it. He was not a teacher of the law but an obedient disciple of the law, so that by his obedience he might redeem those who were under the law. He was the one acted upon, and not an agent, in respect to the law. He bore its condemnation and delivered us from its curse.
Luther makes a helpful distinction here that many misunderstand. While Jesus did teach the law, this was not his main purpose in the incarnation. In other words, Jesus was not just “a good moral teacher”, as many say. Jesus himself denied this claim. His main mission was to deliver those who were under the law. And he did this by obeying its demands perfectly, and by dying under its curse — this was all done for us. Luther finishes his section on this verse, saying, “to teach the law and to perform miracles are particular benefits of Christ, [but are] not his main reason for coming into the world”. Christ came to to deliver us from condemnation, and he did it through representative obedience and vicarious death.
Phillip Ryken expounds on this principle further, saying,
[Christ] was born “under the law”. By his birth he was required to keep the whole Torah, which he did with total perfection. Jesus kept the whole law for his people. He was circumcised on the eighth day, as the law required. He never broke even one of the Ten Commandments. He followed the biblical pattern of worship. He went to Jerusalem to keep the feasts. He celebrated Passover. He did everything the law required.
Jesus even died under the law. For God’s Son, coming under the law included accepting the death penalty his people deserved for breaking it. This is what Paul explained in chapter 3[:13], when he said, Christ redeemed us from the curse of the law by becoming a curse for us”. When Christ came under the law, he also came under its curse. He not only kept the whole law for his people, but also suffered the punishment due to their sins.
Oddly, many believe that Jesus was opposed to religion. This isn’t really true. Grace and religion (earning God’s love through strict obedience) may be opposed. But this is only because Christ was the perfect law obeyer. He was the perfect Jew. He was the one in whom God was “well pleased” (Mt 3:17). And because of that, we are under grace. Because by virtue of faith in Christ, we receive his perfect obedience and death to the law, thereby being redeemed from the curse of the law.