“Not so.” These words were apparently omitted from the Hebrew text in a copyist’s error, but they are preserved in the Septuagint, Aramaic, and Vulgate versions. Some English versions, including the REV, include them (cp. Douay-Rheims; ESV; NIV; NLT; NRSV; Rotherham; RSV).
“appointed a sign for Cain.” The “mark” on Cain has been very misunderstood. Taking time to examine specific words in Genesis 4:15 will help us understand what it is saying. Cain would have been killed for his high treason against God, but God intervened so that he would not be killed, and said, “Not so” (the words “Not so,” in many English versions are taken from the sense of the Hebrew text—see the note in Bullinger’s Companion Bible—and from the Septuagint, Aramaic, and Vulgate versions.)
To ensure His statement would come to pass, God established a pledge or sign on Cain’s behalf so that he would be protected from the immediate wrath of God and people, a wrath Cain deeply deserved. To understand that God established a sign or pledge for Cain, we must carefully examine the Hebrew text of Genesis 4:15. Many versions read, that God “put a mark on Cain,” but that is not the proper translation. For one thing, the word “put,” should, in this context, be translated “appointed” or “established.” The Hebrew word is sim (#07760 שִׂים) and it occurs more than 550 times in the Old Testament. It has a large semantic range and is translated more than 30 different ways in the KJV. Its meanings include “appoint,” “ordain,” and “establish,” and in the context of the “mark” on Cain it is best understood as “appoint” or “establish.” God did not “put” a mark on Cain, but rather “established” a sign or pledge for him.
Also, the word usually translated “on,” should be “for,” meaning that God established a sign for Cain, i.e., on his behalf to keep him from being killed. The Hebrew prefix translated “on” in the phrase “mark on Cain” (NIV) is the Hebrew letter “L,” a prefix so flexible that the Brown-Driver-Briggs Hebrew Lexicon devotes eight and a half pages to defining it. Nevertheless, the first definition they give is, “to, towards, for,” and that is its meaning in this verse. It was a pledge or sign to or for Cain, i.e., to him and on his behalf.
Also, the word “mark” is not a physical mark. The Hebrew word is oth (#0226 אוֹת), and it means a sign, pledge, or token, not a physical mark like a tattoo or something. For example, the stars in the heavens are to be for “signs,” that is, they are to point to times and seasons (Gen. 1:14), they are not “marks” in heaven. If God had meant to say there was a physical mark on Cain, the Hebrew text would have employed the word tav as it does in Ezekiel 9:4 (“Go throughout the city of Jerusalem and put a mark (tav) on the foreheads of those who grieve”) or perhaps kethobeth, an imprinted writing (Lev. 19:28). The Septuagint, the Greek translation of the Old Testament done about 250 BC, supports the fact that this was not a “mark.” The Greek word is semeion, which means a sign, token, or indication by which something is known. So, for example, when Jesus turned the water into wine at Cana, it was referred to as a “sign” (John 2:11; sometimes mistranslated as “miracle”), because it pointed to him as Messiah. Had the translators of the Septuagint thought the “mark” on Cain was physical, they would have used charagma, a physical mark or impression, like the “mark” of the beast (Rev. 13:17).
No physical mark would keep Cain from being killed. Even if the mark were self-explanatory, like a sign saying, “Do not kill,” there would be no guarantee people would obey it. Furthermore, the “mark” would not only have to keep Cain from being killed by others, but it would have to protect all those who through the ages would follow “the way of Cain” (Jude 11) and become children of the Devil. Finally, if the “mark” on Cain were a physical mark it would be easy to tell those people who were children of the Devil—just look for the mark on them!
Properly rendered, the Hebrew text should be translated, “And the LORD established a pledge for Cain (i.e., on Cain’s behalf), or perhaps, “And the LORD appointed a sign for Cain,” (as per the English Revised Version). The Bible does not tell us exactly what the sign or pledge that God established is, but it kept Cain and others who committed the unforgivable sin from being killed by all who meet them.
It is very important that we understand why God interceded for Cain. If Cain’s act of taking the Devil as his lord was worthy of death, why would God delay that judgment and justice? The answer is that God has given mankind genuine freedom of will, and He allows people to choose how and whom they worship, even if those choices are evil. God’s fairness allows people who choose not to worship Him to continue to live. If everyone who chose not to worship God was executed, then God would in essence be saying, “You have two choices: worship Me or die.” Then many who “chose” to worship God would be doing so out of fear of punishment instead of love for Him. God wants people to worship Him out of their love for Him, not because they are afraid that if they do not worship Him then they will suffer horrible consequences. God is love, and love is righteous and just, so He allows people to turn away from Him even if in doing so they support His archenemy. Of course, there will be a Day of Judgment when everyone will be rewarded or punished for what they have done, but the wicked are so arrogant that they are content to remain wicked, denying their wickedness, and/or denying the Judgment.