What was the mark of Cain?
This particular event has interpretations that range from silly guesswork to downright ridiculous assumptions. No one can say with certainty it is just speculation.
The Targum of Jonathan ben Uzziel says the sign was from the great and precious name, probably one of the letters of the word Yahweh.The Talmud say that it was the last Hebrew letter "taw" marked on his forehead, which signified his contrition. One rabbi thought it was horn that grew out from his forehead. More modern interpretations say his skin color was changed, or that the mark was actually a number, six hundred and sixty six. etc.
Because he killed his brother The Lord said:
Gen. 4:12-17 "When you till the ground, it shall no longer yield its strength to you. A fugitive and a vagabond you shall be on the earth." Cain said to the LORD, "My punishment is greater than I can bear! "Surely You have driven me out this day from the face of the ground; I shall be hidden from Your face; I shall be a fugitive and a vagabond on the earth, and it will happen that anyone who finds me will kill me." And the LORD said to him, "Therefore, whoever kills Cain, vengeance shall be taken on him sevenfold." And the LORD set a mark on Cain, lest anyone finding him should kill him. Then Cain went out from the presence of the LORD and dwelt in the land of Nod on the east of Eden.”
Cain went into banishment in a land east of Eden, call Nod. whatever this area of Nod was, it was said to be east of Eden, from the place where Adam and Eve still dwelt, near the garden.
The presence of the Lord seems to imply the entrance of the garden where the cherubim were stationed. Mankind is then being separated as those who will dwell by the presence of God, and those who will have their home elsewhere. Cain was to be on his own. God gave him continuance of life, but he was removed from God's presence, forfeiting God's grace and instructions on his life.
Adam had numerous sons and daughters, Cain anticipates
their children and grandchildren wanting revenge on him for killing their family
This has no relationship to the mark of the beast as some think, it was not a "mark" "on" Cain; the Hebrew says it was a "sign" "for" Cain.. It was not of mark on Cain's skin, nor a change in his skin color.
The word "mark" in Gen. 4:15 is 'owth, which translated means a sign, an omen, a warning, a banner for remembrance.
The original words, literally rendered, are, `the Lord gave a sign, a token or pledge, to Cain, that no one who found him should kill him.’ God assured him of his personal safety by some external sign, granting him continuance of life for his punishment. (Ex.12:13,23; Joshua 2:12) the sign was recognized by others to stop them from avenging Abel.
Just as the
rainbow was the sign of the flood ceasing and a covenant made (Gen. 9:12),this
sign was there to protect him, not curse him. The "curse" was Cain's inability
to cultivate crops and forcibly lead a nomadic life.
There is nor repentance on his part for what he has done, Cain cares only for himself. He complained that this punishment God delivered was "greater than I can bear!” He did not thank God for sparing his life, but feared for it stating “anyone who finds me will kill me." God was being merciful and marked Cain, by a sign that everyone could recognize "lest anyone finding him should kill him" (Gen. 4:15).
Gen 4:15 "And the Lord set a mark upon Cain," should be accurately translated, "And the Lord appointed to Cain a token or sign." this gave him assurance that no person would be allowed to slay him in revenge and would have him live remembering what he had done giving him no relief in his conscience.
The sign was something that distinguished him among men, for all we know the
sign could have been a hat; something unique that was seen. As the story of his
murder went out throughout the people so would the punishment for retaliation,
keeping someone from murdering Cain in revenge for the murder of Abel.