The Fallen Man

Then God (of Abraham, Isaac Jacob) took the man and placed him in the garden of Eden to take care of it. He commanded the man, saying, "You are free to eat from any tree in the garden.
But you must not eat from the tree of the knowledge of good and evil, for when you eat from it, you will certainly die." Genesis 2:15-17 (KJV). 

Now the serpent was more crafty (subtle, skilled in deceit) than any living creature of the field which the Lord God had made. And [a]the serpent (Satan) said to the woman, “Can it really be that God has said, ‘You shall not eat from [b]any tree of the garden’?” And the woman said to the serpent, “We may eat fruit from the trees of the garden, except the fruit from the tree which is in the middle of the garden. God said, ‘You shall not eat from it nor touch it, otherwise you will die.’” But the serpent said to the woman, “You certainly will not die!  For God knows that on the day you eat from it your eyes will be opened [that is, you will have greater awareness], and you will be like God, knowing [the difference between] good and evil.” And when the woman saw that the tree was good for food, and that it was delightful to look at, and a tree to be desired in order to make one wise and insightful, she took some of its fruit and ate it; and she also gave some to her husband with her, and he ate. Then the eyes of the two of them were opened [that is, their awareness increased], and they knew that they were naked; and they fastened fig leaves together and made themselves coverings Genesis 3:1-7 (AMP).

Everyone has sinned and fallen short of God's Glory (Genesis 3:20). Every man, has failed to meet God's expectations of Holiness as He is Holy, because of disobedience. Now days the disobedience has translated itself into murder, uncleanness, covetousness, fornication, adultery and much
more . . .which is considered a sin by the God of Abraham, Isaac, and Jacob (Romans 3:23).

If you want to understand how this "fallen man" happened, you can read about it in Genesis 3 (KJV) and for context Genesis 1-3 (KJV). For understanding read Genesis 6 to see what hideous forms the acts of the fallen man has taken.

And I am concerned that just as the serpent deceived Eve with his cunning, your minds may be led astray from the simplicity that is found in Christ. 2 Corinthians 11:3 (NKJV);

But we are made right with God by His Grace, which is a free gift. We are made right with him through Christ Jesus, who took away our sins. God sent Jesus to be our sacrifice. Jesus showed that God is fair when he forgives sins. He was also showing that He is right in the past when He was patient and did not punish people for their sins. God did this to show in the present time that He is fair. He wants to be the One who makes people right with Him because of their faith in Jesus.