Cain & Abel: Evil Has Entered the World

Eve gave birth to Cain and Abel. Cain was born first followed by Abel. Abel became a herder of flocks and Cain a tiller of the ground. They brought forth a offering to God. God favored Abel's offering over Cain's. 

Cain took his brother out to a field and killed his brother. When God asked Cain where Abel was he told him that he did not know where he was. God banned Cain from the ground. He put a mark on Cain so that he would not be killed at sight.

Cain kills his brother because he is jealous that God favored Abel's offering over his.

This event demonstrates that sin has entered the world.