Goodness and Evil, God's Love and Grace

In the same manner that fallen humanity cannot look upon the face of God because of His holiness, so too God's love for humanity prevents them from looking fully into the essence of evil because of His "common grace." 

The best of human goodness in this life is still odd and strange to heaven, and alarmingly the worst of human evil is a poor expression of what true evil would have us become. 

[6-7 God spoke to Cain: “Why this tantrum? Why the sulking?] 

If you do well, won’t you be accepted? And if you don’t do well, sin is lying in wait for you, ready to pounce; it’s out to get you, you’ve got to master it.”

Genesis 4:7 (The Message translation)