The ‘law of Christ’ is a New Testament phrase. It comes from the writing of the Apostle Paul in Galatians 6:2 “…and in this way you will fulfill the law of Christ” as well as in 1 Corinthians 9:21 “…I do not ignore the law of God; I obey the law of Christ.”
In addition to this, we hear Jesus Himself say this in Matthew 5:17-18 (NIV);
“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 tell you, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished.”
Future more, He told us that the law, the Ten Commandments as given by God to Moses, can be summed up in two commands - love the Lord your God with all your heart and with all your soul and with all your mind, and love your neighbor as yourself (Matthew 22:37-40).
Jesus is the law, He has been the law from the very beginning and will be the law forever. So, whoever practices things that are opposed to the law are opposed to Him. They are those who are lawless. The Word of God calls the one who is lawless the man of sin (1 John 3:4), they are disobedient to Him (1 Timothy 1:9), and He does not know them (Matthew 7:23). He emphasizes this message to those who said they knew God, “So you also outwardly appear righteous to others, but within you are full of hypocrisy and lawlessness.” (Matthew 23:28, NIV) Yet, He reminds those who follow Him, “If you love me, you will keep my commandments.” (John 14:15, ESV)
My friends, in the past we all sinned against the righteousness of God (Romans 3:23) by “Realizing the fact that law is not made for a righteous person but for those who are lawless and rebellious, for the ungodly and sinners, for the unholy and worldly…” (1 Timothy 1:9, NSAB)
However, we should now know that because of what Christ did, we are made righteous with God through His faithfulness (Romans 5:1). We have no excuse to disobey His Word or abuse His grace and mercy to keep on sinning.
The conclusion is this: We are called to keep the law and not to defile the law, for this is the duty of all mankind. (Ecclesiastes 12:13)