Now that God had placed Adam in the garden, gave him authority, specific direction and even a companion, a wife that was comparable to him we begin to discover the actual root of bad things being unleashed upon all mankind...
Now the serpent was more cunning than any beast of the field which the LORD God had made. And he said to the woman, "Has God indeed said, 'You shall not eat of every tree of the garden'?" And the woman said to the serpent, "We may eat the fruit of the trees of the garden; but of the fruit of the tree which is in the midst of the garden, God has said, 'You shall not eat it, nor shall you touch it, lest you die.'" Then the serpent said to the woman, "You will not surely die. For God knows that in the day you eat of it your eyes will be opened, and you will be like God, knowing good and evil."
One of the unique attributes that God had given to mankind was the freedom of choice. Adam was a spirit with a soul encased within a body, his spirit was perfect and because of this his soul and body (flesh) were under full submission to his spirit. We do not know to this point in scripture why Satan chose to whet the appetite of the woman with his deception, but his false truth claims cause her soul to reason between two claims of truth, God's and Satan's. Finally we see that she responds...
So when the woman saw that the tree was good for food, that it was pleasant to the eyes, and a tree desirable to make one wise, she took of its fruit and ate. She also gave to her husband with her, and he ate. (Genesis 3:6)
Unfortunately for mankind she chose wrong, but that is not the whole of it. Notice that when the woman ate of the forbidden tree she also gave it to her husband WITH HER, and he ate. Against some popular teaching that says Adam was not around when his wife was being seduced is not an accurate account. In fact he was WITH HER and watch the entire deceptive work of Satan unfold and did nothing to prevent it. Remember, he had the authority not Satan and did not use it against Satan's attack. Think about it, all he had to do was to speak and Satan would have had to obey. He could have said, "Satan get off the earth and never return" and that would have been the end of it forever. However, he chose to disobey the command of the LORD and by this act of disobedience forfeited his God given rights and authority to Satan. Now instead of Satan being under mans authority man was now under Satan's authority. Man not only gave up his authority but also his connection with God because he was now spiritually dead. God is Spirit and relates to mankind in spirit.
With Satan in charge of mans affairs so to speak let's look at what the Bible reveals as his nature. He is adversary, hater, opponent, enemy, accuser, slanderer, whisperer, enchanter, beguiler, tempter, liar, thief, murderer, do we get the point? His activities are to slander God to man and man to God; oppose God's ministers, pervert the Word of God, hold man captive through oppression, deception, possession, torments, vexing and buffeting. Because man is spiritual dead, Satan manifests these things through the soul (mind, will and emotions) and the body (the flesh). Even though there is much more evidence in the Bible that bad things do not come from God, we could actually stop here and logically conclude that all the bad things on earth are the result of the fall of man, that is, the destructive nature of sin and Satan.
The good news is that the LORD Jesus Christ conquered Satan and his gang and has made provision for all man to be set free by being turned from darkness to light, and from the power of Satan to God, through faith in Jesus Christ.