When you ask, “What does the law of God require?” the short answer is perfect obedience. Now, that sounds daunting, but we have to understand the context in which the law was given. It was given in the context of grace, God’s saving initiative. When God rescued Israel from Egypt and brought them to Sinai and declared, “If you obey my voice and keep my covenant,” he essentially then said, “I will be your God and you will be my children.” So the context of the law is God’s saving initiative. The perfect obedience that the law demands is a response to God’s saving initiative, and it is a wholehearted devotion.
The way that the Old Testament puts it is: “Love the Lord your God with all your heart and with all your soul and with all your might” (Deut. 6:5). The context of grace motivates a response of wholehearted devotion to the God who saves. It is a response of faith that is called love. And that love flows to love of neighbor as well.
There is only one problem. We cannot obey perfectly. But there is good news. In Jeremiah 31 God says that he will write the law on his people’s hearts. In Ezekiel 36 God further explains: “I will remove the heart of stone from your flesh and give you a heart of flesh. And I will put my Spirit within you, and cause you to walk in my statutes” (vv. 26–27). These promises are linked to a new covenant that God would initiate through a promised king from David’s line. The New Testament reveals that the promised King who inaugurates this new covenant is Jesus.
Jesus came to do what we ourselves could not do. While remaining fully God, Jesus came from heaven and took on our humanity in order to save us (Heb. 2:14–18). As our human representative, Jesus fulfilled the law of God by perfectly obeying God’s commands and by paying the penalty of death that all lawbreakers owe. The gospel is an announcement that all who confess that they are guilty of breaking God’s law and turn away from their sins and trust in Jesus have their sins forgiven and Jesus’s perfect obedience accounted to them.
Through his life, death, burial, and resurrection, Jesus inaugurated the new covenant with its promises of a new heart (Jeremiah 31) and the indwelling of God’s empowering Spirit (Ezekiel 36). Our only hope of fulfilling what the law requires is the new birth that was promised in the new covenant. Those who are born again to new life in Christ have been granted a new heart and God’s indwelling Spirit, which empowers obedience.
The good news is that under the new covenant, God’s people are empowered to obey God’s law. Once again, we see that the commands of God don’t establish a relationship with God. Obedience is our response to God’s saving work. It is a loving response of faith. God has saved us in Jesus Christ, and we respond by trusting him in loving obedience.
Loving the Lord God with all your heart, mind, soul, and strength is the first great branch of Christian righteousness. You shall delight yourself in the Lord your God; seeking and finding all happiness in Him. You shall hear and fulfill His word, “My son, give me your heart.” And having given Him your inmost soul to reign there without a rival, you may well cry out in the fulness of your heart, “I will love You, O my Lord, my strength. The Lord is my strong rock; my Savior, my God, in whom l trust.” The second commandment, the second great branch of Christian righteousness, is closely and inseparably connected with the first: “Love your neighbor as yourself.” Love—embrace with the most tender goodwill, the most earnest and cordial affection, the most inflamed desires of preventing or removing all evil and bringing every possible good. Your neighbor—not only your friends, kinfolk, or acquaintances; not only the virtuous ones who regard you, who extend or return your kindness, but every person, not excluding those you have never seen or know by name; not excluding those you know to be evil and unthankful, those who despitefully use you. Even those you shall love as yourself with the same invariable thirst after their happiness. Use the same unwearied care to screen them from whatever might grieve or hurt either their soul or body. This is love.