As Cain did not believe in God nor does Cain's descendants, but only wants to do things their way.
As Cain wanted to do his offering his way and not Gods way.
As Cain's descendants wants to worship God their way and not God's way.
As many people wants to follow man's teachings and not the teachings of God's.
And Christ Jesus.
Interpreting what God's teaching means has always been a problem. The Bible was not directly written by God but by men and translators pretending to know what God was thinking. The mind of God is way beyond man's comprehension. I think the Bible should not be read out of the historical context in which it was written. But the essential message of the Bible that morality is important is still relevant today.
Does this make me an evil person? If you say "yes" then how can you live your life with this bit of evil as your guide:
No. 1:St Paul’s advice about whether women are allowed to teach men in church:
“I do not permit a woman to teach or to have authority over a man; she must be silent.” (1 Timothy 2:12)
No. 2: In this verse, Samuel, one of the early leaders of Israel, orders genocide against a neighbouring people:
“This is what the Lord Almighty says... ‘Now go and strike Amalek and devote to destruction all that they have. Do not spare them, but kill both man and woman, child and infant, ox and sheep, camel and donkey.’” (1 Samuel 15:3)
No. 3: A command of Moses:
“Do not allow a sorceress to live.” (Exodus 22:18)
No. 4: The ending of Psalm 137, a psalm which was made into a disco calypso hit by Boney M, is often omitted from readings in church:
“Happy is he who repays you for what you have done to us – he who seizes your infants and dashes them against the rocks.” (Psalm 137:9)
No. 5: Another blood-curdling tale from the Book of Judges, where an Israelite man is trapped in a house by a hostile crowd, and sends out his concubine to placate them:
“So the man took his concubine and sent her outside to them, and they raped her and abused her throughout the night, and at dawn they let her go. At daybreak the woman went back to the house where her master was staying, fell down at the door and lay there until daylight. When her master got up in the morning and opened the door of the house and stepped out to continue on his way, there lay his concubine, fallen in the doorway of the house, with her hands on the threshold. He said to her, ‘Get up; let’s go.’ But there was no answer. Then the man put her on his donkey and set out for home.” (Judges 19:25-28)
No. 6: St Paul condemns homosexuality in the opening chapter of the Book of Romans:
“In the same way also the men, giving up natural intercourse with women, were consumed with passion for one another. Men committed shameless acts with men and received in their own persons the due penalty for their error.” (Romans 1:27)
No. 7: In this story from the Book of Judges, an Israelite leader, Jephthah, makes a rash vow to God, which has to be carried out:
“And Jephthah made a vow to the Lord, and said, ‘If you will give the Ammonites into my hand, then whoever comes out of the doors of my house to meet me, when I return victorious from the Ammonites, shall be the Lord’s, to be offered up by me as a burnt-offering.’ Then Jephthah came to his home at Mizpah; and there was his daughter coming out to meet him with timbrels and with dancing. She was his only child; he had no son or daughter except her. When he saw her, he tore his clothes, and said, ‘Alas, my daughter! You have brought me very low; you have become the cause of great trouble to me. For I have opened my mouth to the Lord, and I cannot take back my vow.’” (Judges 11:30-1, 34-5)
No. 8: The Lord is speaking to Abraham in this story where God commands him to sacrifice his son:
‘Take your son, your only son Isaac, whom you love, and go to the land of Moriah, and offer him there as a burnt-offering on one of the mountains that I shall show you.’ (Genesis 22:2)
No. 9: “Wives, submit to your husbands as to the Lord.” (Ephesians 5:22)
No. 10: “Slaves, submit yourselves to your masters with all respect, not only to the good and gentle but also to the cruel.” (1 Peter 2:18)
Genocide, slavery, and sending concubines out to be gang raped has to be considered to be evil by today's standards. The Bible getting slavery wrong is a pretty big deal. But as I said, if read as metaphor not taking out of the historical context in which it was written, the message morality is important is still relevant.