Look at Job for a moment:
We know something about Job from the opening of the book. He was wealthy and he was 'blameless and upright'. He 'feared God and turned away from evil'.
But lets focus briefly on his suffering and the source of that suffering.
6 Now there was a day when the sons of God came to present themselves before the LORD, and Satan also came among them. 7 The LORD said to Satan, "From where have you come?" Satan answered the LORD and said, "From going to and fro on the earth, and from walking up and down on it."
This is somewhat of a curious scene, but it seems that the sons of God and Satan are required to give an account of their doings before God. We see that Satan has been going to and fro on the earth. This is the picture that Peter paints in 1 Peter 5:8. He mentions the devil prowls around like a roaring lion, seeking someone to devour. That's his purpose.
So we can assume that Satan was roaming the earth seeking someone to devour. Now it gets a little tricky.It seems as though God throws Job under the bus. Look at verse 8:
And the LORD said to Satan, "Have you considered my servant Job, that there is none like him on the earth, a blameless and upright man, who fears God and turns away from evil?"
Has God decided to give the devil someone to occupy him. He certainly has that right. But it appears as if Satan knew Job very well. He responds to God in verses 9-10 in this way:
9 Then Satan answered the LORD and said, "Does Job fear God for no reason? 10 Have you not put a hedge around him and his house and all that he has, on every side? You have blessed the work of his hands, and his possessions have increased in the land.
So Satan is very aware of Job, his fortune and his fear of God. Indeed he had certainly considered Job. God knew this. Psalm 94:11 says that God knows the thoughts of man, no doubt He knows the thoughts of the devil as well. Much like Jesus knew the thoughts of His disciples and His opponents and often answered their questions before being asked, God here answers Satan's request before it is made. In Job 2:3, God says that Satan incited Him against Job. So we can see Satan's desire to destroy Job and God's will to allow him to try.
We see also Satan's awareness that ultimately, its God's decision. In 1:11, he tells God:
But stretch out your hand and touch all that he has, and he will curse you to your face."
To which God's reply is (v.12):
"Behold, all that he has is in your hand. Only against him do not stretch out your hand."
Here, Satan is given permission to take whatever possessions Job has, including family. Only he can not touch Job at all. In 2:5-6, Satan is frustrated with the results (Job praised God) and requests permission to go further. God concedes and allows Satan to touch Job, only he can not take his life.
In 2:10, a stricken and distraught Job acknowledges the absolute sovereignty of God by answering his wife's charge to 'curse God and die':
'Shall we receive good from God, and shall we not receive evil?'
So. Evil. Disaster. Suffering. Where does it come from? It comes from God. Many other Scriptures teach us this. The devil desires to devour us and destroy us, but he can go only so far as our Sovereign Lord will allow him. And in the end, this will work for our good and God's glory.