God's will for mankind is salvation-the eternal union of our soul with God. One of the first things the Bible tells us is that human beings are by nature sinful and in need of the righteousness of God. It says that all mankind has sinned and fallen short of the glory of God. There is none that understandeth, there is none that seeketh after God. The Biblical account of man's historic fall out of a state of righteousness and holiness into a state of sin and condemnation explains the dark side of man.
People lie, cheat, steal, murder and rape because they are sinners by nature .
Sin is a power that came into the world through Adam's disobedience. It's simply disobedience to God's Word. Sin rules the world, enslaves and controls people. It's effect on all mankind is separation from God. Therefore, in order to be reunited with God, we must be cut off from sin and set apart to righteousness.