Ever since the beginning of the age of  mankind, God has been warning us of the consequences of sin. We find that in the scriptures that it was said  "For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord." 

Romans 6:23 (King James Version)

We know that God always sends a warning to let people know what will happen if they continue in sin and continue to be disobedient towards him.