Is the law of Christ different from the law of Moses? If so, what is the law of Christ?

from the old testament

• The Mosaic Law (Torah) given through Moses included moral, ceremonial, and civil commands for Israel (Exodus 20; Leviticus; Deuteronomy 5–6). It set God’s standards of holiness and justice for His people, pointing to God’s character and the need for obedience.
• The heart of the law—love for God and neighbor—was emphasized as the ultimate requirement of the Law, which Jesus fulfilled (Deuteronomy 6:5; Leviticus 19:18).
• The prophets consistently warned that outward ritual compliance without a transformed heart was insufficient (Hosea 6:6; Jeremiah 7:21–23).
• God promised a new covenant in which He would write His law on people’s hearts (Jeremiah 31:33; Ezekiel 36:26–27), anticipating the law of Christ.

from the new testament

• The law of Christ, referred to in Galatians 6:2 and 1 Corinthians 9:21, is much simpler (in detail, but not in application) than the law of Moses. These are the only places in Scripture where the law of Christ is specifically mentioned, and it is not defined in either of the passages.
• Biblical scholars generally agree that the law of Christ is composed of the basic commandments Jesus quoted in Matthew 22:37–40, "And he [Jesus] said to him, 'You shall love the Lord your God with all your heart and with all your soul and with all your mind [Deuteronomy 6:5]. This is the great and first commandment. And a second is like it: You shall love your neighbor as yourself [Leviticus 19:18]. On these two commandments depend all the Law and the Prophets.'" The heart of the Mosaic law foreshadowed the law of Christ.
• In another account of the incident (Mark 12:28–34), the questioner agrees with Jesus' statement that all the rest of the Law (the law of Moses) and the Prophets were based on these two laws.
• Jesus Himself said, "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. For truly, I say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished" (Matthew 5:17–18). So, the law of Christ cannot be different in nature from the law of Moses but rather an enlightenment of what the law of Moses really means to all men.

implications for today

The law of Christ supersedes the law of Moses, but it does not change it. It boils down the law of Moses to what Christians should follow: love God and love others. Jesus freed us from the hundreds of rules in the law of Moses. But loving God with our entire being and loving others as ourselves is the most difficult part of keeping the law of Moses. In fact, it is impossible without God doing it through us.

Some people have taken the fact that we, as Christians, are not under the law of Moses as an excuse to sin. In fact, Paul had to deal with this early on in Romans 6. In verse 15, he says, "Are we to sin because we are not under law but under grace?" He goes on to answer, "By no means!" Since, as Jesus said, the whole law of Moses depends on the commands to love, and we are commanded to love as Jesus loved us (John 13:34–35), we cannot use our freedom from the law of Moses as an excuse for sin. Instead, because of that love, we will want to avoid sin (which separates us from God), and we will want good for mankind. We will not be tied legalistically to rules, but we will want to please God and show His love to everyone.