The LORD said to Cain:
“What’s wrong with you? Why do you have such an angry look on your face? If you had done the right thing, you would be smiling. But you did the wrong thing, and now sin is waiting to attack you like a lion. Sin wants to destroy you, but don’t let it!”
Cain said to his brother Abel, “Let’s go for a walk.” And when they were out in a field, Cain killed him.
Afterwards the LORD asked Cain, “Where is Abel?”
“How should I know?” he answered. “Am I supposed to look after my brother?”
Then the LORD said:
“Why have you done this terrible thing? You killed your own brother, and his blood flowed onto the ground. Now his blood is calling out for me to punish you. And so, I’ll put you under a curse. Because you killed Abel and made his blood run out on the ground, you will never be able to farm the land again. If you try to farm the land, it won’t produce anything for you. From now on, you’ll be without a home, and you’ll spend the rest of your life wandering from place to place.”
“This punishment is too hard!” Cain said. “You’re making me leave my home and live far from you. I will have to wander about without a home, and just anyone could kill me.”
“No!” the LORD answered. “Anyone who kills you will be punished seven times worse than I am punishing you.” So the LORD put a mark on Cain to warn everyone not to kill him. But Cain had to go far from the LORD and live in the Land of Wandering, which is east of Eden. (Genesis 4:6-16)
Eye for eye, tooth for tooth. Cain had murdered his brother and he deserved to die. All the ancient law codes, from Egypt to Mesopotamia included death as the sole penalty for murder. After the Great Flood, God ordered capital punishment for murder. The death penalty was part of the covenant God made with Israel in the time of Moses. Nevertheless, over and over, those guilty of the most heinous crime imaginable were granted mercy instead of vengeance. Moses killed an Egyptian overseer, but God did not demand his execution. David murdered Uriah, and he was forgiven. But before all of that, we have the example of Cain who murdered his younger brother.
God had rejected Cain’s offering, but had accepted his brother’s. Why? Not because of the kind of offering that Cain brought to God, but because of the kind of heart he had brought to him. God warned Cain about his anger. Rather than repenting, Cain gave into it and murdered his sibling.
God did not order Cain’s execution. Cain’s punishment was exile from his people and from his chosen profession as a farmer. But God protected Cain from human vengeance. Rather than allowing justice—eye for eye—God granted Cain mercy.