The story of Cain and Abel is a continuation of the Fall narrative of Genesis 3, and functions as a description of the first manifestation of violence in humankind’s history. According to Genesis 4, Eve gave birth to two children, first to Cain, and then to Abel,
“Adam made love to his wife Eve, and she became pregnant and gave birth to Cain. She said, “With the help of the Lord I have brought forth a man.” Later she gave birth to his brother Abel.” (4:1-3)
In the span of just a single verse, readers learn that when the two boys grow up they pursue different paths: “Now Abel kept flocks, and Cain worked the soil” (4:2). Cain becomes an agriculturalist whose responsibility it is to till the soil. Abel becomes a pastoralist, a person who is a keeper of sheep and goats. As the story continues the brothers bring sacrificial offerings to God which they take from their own work,
“And Abel also brought an offering—fat portions from some of the firstborn of his flock. The Lord looked with favor on Abel and his offering, but on Cain and his offering he did not look with favor. So Cain was very angry, and his face was downcast” (4:4-6).
In this verse God is pleased with Abel’s offering but not with what is offered by Cain. Cain becomes angry and God, noticing Cain’s anger, warns him that sin is crouching at the door, and that he must avoid its temptation.
One might assume that Cain’s anger at God’s displease of his offering turns to jealousy over his brother, Abel. Cain then lures Abel out into a field where he murders him (4:8). When God later inquires as to where Abel is, Cain asks: “Am I my brother’s keeper?” (4:9) Cain’s response seems to mock his (now dead) brother, given that it was Abel who was the “keeper,” particularly the keeper of the flock. However, God knows what Cain had done to his brother and banishes him from the land,
“The Lord said, “What have you done? Listen! Your brother’s blood cries out to me from the ground. Now you are under a curse and driven from the ground, which opened its mouth to receive your brother’s blood from your hand. When you work the ground, it will no longer yield its crops for you. You will be a restless wanderer on the earth” (4:10-13).
Cain then fears that should he be exiled from the land and away from God’s presence he will lose the protection he previously enjoyed, and that someone will find him and kill him. But God puts a protective mark on Cain and says that no-one who will find him will murder him (4:16). Cain thus ventures “out from the Lord’s presence and lived in the land of Nod, east of Eden” (4:16).
This text is the first mention of a murder in the Bible and condemns such an act on the premise that life is sacred. The next recorded killing occurs several generations later where Lamech, a descendant of Cain, kills a man who had wounded him (4:23)
Schneider, T. 2018. The Bible Book. p. 36-37.