The first two children Adam and Eve had were Cain and Abel. As they grew up, Cain took to cultivation and Abel to rearing sheep. Adam and Eve may have learned during the course of their interaction with God after the Fall, the practice of offering sacrifices to God when they felt guilty, thankful, needy, etc. Cain and Abel too brought their sacrifices to God, Cain from the grain he got from his field and Abel a sheep from his fold. God who had been observing these boys from their childhood was not happy with Cain, and He did not accept his offering. But He accepted Abel and his offering. This seemed to be unfair to Cain and he was very jealous and upset with his brother Abel.

God could see what was coming and He tried to warn Cain. He suggested that Cain should examine why he was angry with his brother and deal with it, because otherwise it was going to get the better of him. God was trying to give him an opportunity to overcome it. But Cain could not understand this, and he went on to get Abel alone into a field where he turned on him and killed him.

God took Cain to task for what he had done, and told him that from then onwards he would be a wanderer on the earth. This was an attempt from God to wake up Cain and help him to repent, recognising the seriousness of what he had done. But even after this, Cain felt no guilt before God for what he had done to his brother. He shrugged it off saying that he was not obliged to be responsible for his brother. The only thing he felt bad about was that the punishment God placed on him was too much. He hardened his heart, turned away from the presence of God, married his sister (there was no one else to marry at that time), and started raising a family which ultimately became big enough to set up several cities. Violence began to increase.

God started a new line of people from Seth, another son of Adam, and their generations began to seek after Him and call on His name.