Christ, through the prophet Jeremiah, foretold that He would write His law on our hearts under the new covenant (Jeremiah 31:33; Hebrews 8:10), but does this mean that we will automatically obey God's law (e.g. the ten commandments) simply by accepting in faith that Jesus is our personal savior?
Let us notice what one of the inspired writers of the New Testament had to say about all the commandments, not just the ten of Exodus 20. The apostle James states that unless we are doers of God's word and not just hearers (James 1:22) we are deceiving ourselves (James 1:22). In verse 25, he tells us how to be doers of the word, which is by looking into the perfect law of liberty and continuing in it. In other words, we are to LOOK into God's inspired word, the Bible, to find the "perfect law of liberty" and then KEEP that law!
Does this contradict Christ's statement that He will write His law on our hearts? No! However, it does provide insight into the way in which Christ writes it. It shows that, upon our acceptance of His sacrifice, Christ does not simply turn us into spiritual robots who automatically have knowledge of what His law is and how to keep it. Rather, after conversion, He expects us to study the Bible so that we can understand the perfect law of liberty and then abide by it.
However, what is the perfect law of liberty to which James referred? In Matthew 22:36 - 39, Christ reveals what are the two greatest commandments. The first one is we are to love God with all our heart, soul and mind; and second, we are to love our neighbors as ourselves. Although this tells us that the overall principle of the law is outgoing love toward God and fellow man, it does not give us the details of how we are to show that love.
In 1John 5:3, the details of how to love are defined in relation to obeying the ten commandments. However, which ones is he referencing? Undoubtedly, to the laws of GOD which, when transgressed, result in sin (1John 3:4). The apostle Paul tells us which ones these are. He writes that he would not have known what sin was except the law told him not to covet (Romans 7:7). This directly references one of the laws found in Exodus 20, the same ones James was referring to when he wrote about the perfect law of liberty.
Did the commandments exist BEFORE the time of the Exodus? A good place to begin is in the Garden of Eden. Paul tells us it was there that sin first entered the world (Romans 5:12 - 14). Three important points can be ascertained from this section of scripture. The first is that sin entered the world through Adam (verse 12). The second is that until there was law, sin could not be imputed (verse 13). The third is that DEATH reigned from Adam to Moses (verse 14).
For Paul to make these statements means that there had to have been a law in place from the very beginning. If there had been no law, there could not have been sin (verse 13 and Romans 4:15). Keep in mind that sin is the transgression of the law (1John 3:4). There was definitely sin before Moses was born because its penalty was administered upon every man and woman from the time of Adam forward (verse 14 and Romans 6:23).
Which of God's commandments did Adam and Eve break? By listening to and following Satan's deception, they disobeyed the FIRST one by putting another god before the one true God. They broke the FIFTH one by dishonoring their Father (Luke 3:38). Because they stole something that was not theirs, they broke the EIGHTH law. Finally, they broke the LAST of God's commands by lusting for the food, and coveting the wisdom it could bring them. Shortly after creation, the first two human beings had already transgressed four of the commandments found in the Decalogue!
The NEW Covenant
It is abundantly clear that God's law is not confined to the old covenant. Specific examples from the Bible make it evident that they were in effect from the very start of the human race. They formed the core of the old covenant not because they pertained only to the nation of Israel, but because they form the core of all peaceful, happy human existence. As such, they also form the core of the new covenant.
Though many attempt to deny it, the Bible plainly shows that the Ten Commandments are not unique to the old covenant. Rather, they comprise the eternal, immutable laws set in place from the very beginning that reveal to mankind how God expects him to live. They ARE relevant in today's world!