8 Cain spoke to Abel his brother. And when they were in the field, Cain rose up against his brother Abel and killed him. 9 Then the Lord said to Cain, “Where is Abel your brother?” He said, “I do not know; am I my brother's keeper?” 10 And the Lord said, “What have you done? The voice of your brother's blood is crying to me from the ground. 11-12 And now you are cursed from the ground, which has opened its mouth to receive your brother's blood from your hand. When you work the ground, it shall no longer yield to you its strength. You shall be a fugitive and a wanderer on the earth.”

13-14 Cain said to the Lord, “My punishment is greater than I can bear. Behold, you have driven me today away from the ground, and from your face I shall be hidden. I shall be a fugitive and a wanderer on the earth, and whoever finds me will kill me.” 15-16 Then the Lord said to him, “Not so! If anyone kills Cain, vengeance shall be taken on him sevenfold.” And the Lord put a mark on Cain, lest any who found him should attack him. 17 Then Cain went away from the presence of the Lord and settled in the land of Nod, east of Eden. Cain knew his wife, and she conceived and bore Enoch. When he built a city, he called the name of the city after the name of his son, Enoch. Genesis 4:8-17 English Standard Version

When God accepted his brother Abel's offering, but not the offering he brought, Cain became angry. God told him if he chose the right way he would also be accepted, but if he did wrong then sin would be like a beast ready to overpower him. Cain rejected God's warning and it led to the violence we see in vs 8. Some ancient manuscripts say that when Cain spoke to Abel he actually said “Let us go out to the field.” That suggests a premeditated act. How does God view such an act of violence? (vs 10)

It was surely a cry for justice, and it reached the ears of God. God passed sentence upon the wrongdoer in the form of banishment and hard labour. (vs 11-12) Cain certainly took what God said as punishment, and it caused him to fear that others would take revenge on him for what he'd done. (vs 13-14) We aren’t told what the mark was that God plut on Cain. But do God's words in vs 15-16 mean capital punishment is wrong? Should murderers just be banished from society and be put in prison for the rest of their life?

I would say no. At this time there was no commandment clearly forbidding murder – though Cain must've known in his heart it was a terrible thing to do. God was forbidding others from taking personal revenge. After the worldwide flood in Noah's day God gave instructions regarding the punishment for murder to Noah and his sons, and the generations that would follow them. He said: “'For your lifeblood I will require a reckoning! From every beast I will require it, and from man. From his fellow man I will require a reckoning for the life of man.' Whoever sheds the blood of man, by man shall his blood be shed, for God made man in his own image.” (Genesis 9: 4-6) In Revelation 6:10 we read of the souls of people slaughtered for their faith in Jesus also crying out to God and saying: “How long before you will judge and avenge our blood on those who dwell on the earth?” The death penalty is a serious issue, but it is not contrary to God's will.

There's another point we should note from this section. What does vs 17 say about Cain?

Cain was married. He would've married one of the daughters born to Adam and Eve. This was at the start of the human race and there was no law yet that forbade such a marriage. The world was still young and genetic defects that could lead to deformities had not yet developed. The Bible’s focus is on the people through whom God was going to bring about the one who would bruise the serpent's head. But Genesis 5:4 says Adam lived to be 930 - “and had other sons and daughters.” When it says Cain 'built a city', we mustn't think in terms of London. Yet it does suggest the population grew quickly in those days and people soon built places to live together. What cities became through the millennia shows the sorrow sin brought into the world, and how sad it is that mankind was banished from the garden where God first put Adam.