The Mosaic Law is different to the moral law. So which law operated from the very beginning of human history. Although they were not written down until Mount Sinai, the Ten Commandments were understood and honored by the earliest patriarchs. Even Cain knew that it was a sin to kill, because God told him that “sin lieth at the door” (Genesis 4:7) after he murdered his brother.
It is impossible for sin to exist where there is no law. The Bible teaches, “for where no law is, there is no transgression” (Romans 4:15). Again we are told, “Whosoever committeth sin transgresseth also the law: for sin is the transgression of the law” (1 John 3:4). This principle is amplified further by Paul’s statement that “I had not known sin, but by the law: for I had not known lust, except the law had said, Thou shalt not covet” (Romans 7:7).
These verses nail down the truth that no sin can be imputed where the law is not in effect (But which law). killing is one of the 10. Joseph revealed that he was aware of the binding claims of the same law. He said to Potiphar’s wife, “how then can I do this great wickedness, and sin against God?” (Genesis 39:9). He knew adultery was sin.
Abraham was commended by God in these words: “Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws” (Genesis 26:5). It is very obvious that the law which Abraham faithfully obeyed was not the law of Moses, because that law was not given until 430 years later. many of the Ten Commandments existed before Abraham, neither is it possible for us to conceive that great, godly Abraham was not acquainted with the basic issues of right and wrong contained in the Ten Commandments.
It is absolutely certain that another law was added 430 years later, and it was in addition to the one Abraham kept so diligently. “And this I say, that the covenant, that was confirmed before of God in Christ, the law, which was four hundred and thirty years after, cannot disannul, that it should make the promise of none effect” (Galatians 3:17).
The context of this verse indicates that Paul is talking about the ceremonial law rather than the moral law of the Ten Commandments. In verse ten, he refers to the curses “which are written in the book of the law.” there are no curses recorded in the law written on stone.
Can we find further confirmation that this later law was indeed the law of Moses? The answer rests in Galatians 3:19. “Wherefore then serveth the law? It was added because of transgressions till the seed should come to whom the promise was made ...” Here we have two significant facts set forth concerning the law which was added. We are told why it was given and also how long it would remain in effect. These two bits of information is evidence that the law which was added is not the ten commandments. The moral laws (Ten commandments are still convicting people today. and were convicting people before Sinai.
Be honest with yourself. Why would God put the Sabbath commandment in the 10, knowing that only 9 of them apply to all time and people.