What have you done? The voice of your brother's blood is crying out to me from the ground. And now you are cursed from the ground, which has opened its mouth to receive your brother's blood from your hand. When you till the ground, it shall no longer yield to you its strength. You shall be a fugitive and a wanderer on the earth.
The ground would no longer be easy to work and to grow food in. It was cursed. Then Cain cried out to God. He was afraid of being driven away from the presence of God and that whoever found him would kill him. God replied:
Therefore whoever kills Cain, vengeance will be taken on him sevenfold. And the LORD appointed a sign for Cain, so that no one finding him would slay him.
Instead of "appointed a sign for Cain," some translations read "put a mark on Cain." This sign, or mark, was a symbol of agreement, a type of covenant, perhaps a miraculous sign or warning to others. But for Cain, it was protection. The sign was a symbol of God's mercy, compassion and protection. We don't know what the sign was, but there is nothing in the text that would indicate a change in skin color. That is just hate-filled, racist fiction. This was a distinguishing mark or symbol. If I were to wager a guess, I might propose that it could have been something like a cross. We don't know. But what we do know is that this mark was absolutely NOT a curse. It was a blessing. The sign was a symbol of an agreement, a covenant between God and Cain that promised The Lord's protection and that if anyone harmed him, God would be his avenger of blood, the one to make it right. The mark was a sign of God's mercy, compassion and protection, even for a murderer like Cain. This is good news for us, because He has shown this same great compassion on the entire human race through Jesus.
The curse on the ground is the only curse mentioned in the text of Genesis 4 which records these events. God's covenant with Noah removed this curse. Genesis 8:21 records:
I will never again curse the ground for man's sake...
The curse that Cain caused from the ground was lifted after the worldwide flood of Noah's day. That curse no longer exists. The sign he received was a sign of God's promise to protect him. It was the sign of a covenant between God and Cain. This event demonstrates God's amazing mercy and compassion on sinners. For this, we all can be grateful.
Here are links to my other articles in this series against false, racist, theologies: