Genesis 4

Genesis 4...In which 1/4th of the entire human race gets murdered!
Cain is a man of the ground, he works with his hands and grows vegetables... Abel is a shepherd, who tends to his flock... Both are valued jobs, but when it comes to giving God what is his, Abel gives the best of the best, Cain gives God his second best- This displeases God, because God wants our best, God deserves our best!

Realizing that God has not accepted the secondhandedness of Cain's labour, He gets angry at his brother Abel... God makes it clear to Cain what he should have done, as mentioned in verses 6 & 7 - "Then the LORD said to Cain, "Why are you angry? Why is your face downcast? If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must master it." Cain hears what God has to say, but sin has already seeped in and poisoned him...

Cain lures his brother away and then...he kills him! When God meets up with Cain again, God asks him where his brother is... Cain covers it up and states that he is not responsible for what his brother does or where his brother is... Yet God knows all and tells him of it and God curses him and informs him he will no longer be able to be successful...He is now a marked man.
Cain questions God if this means that people will try to kill him, God says that a heavier penalty will take place if Cain is killed... So even though he is a marked man, God will give him security from those who would normally try to kill him.

Cain is blessed...but not directly; his decendents go on to become instrument makers and metal lurgists... All the while Adam and Eve are having more kids, and as the chapter ends it is made clear that "At that time men began to call on the name of the LORD."

I think this is suggesting that life is finally getting harder: Life was hard due to the sins of Adam and Eve, but now murder (of another human) has added to what a human can do...Because of sin.
That is what disturbs me a lot in regards to sin (among other things), the things we say we wouldn't do, we possess the capability to do so... Murder, Anarchy, Self-Immolation, etc.
Thankfully...Thankfully God provided a way out!

Going on by God's strength alone,