WHY GOD LET SATAN TO DO THE TEST ON JOB?

Job, a good man, non-Israelite, who lived in the land of Uz, worshiped God and was faithful to Him. He was careful in not to do anything evil, because he knew the consequences of misunderstanding the Word of God. He was the richest man in the East.
The day in which the heavenly beings appeared before the Lord came, and Satan was there among them. The Lord asked him, "What have you been doing?" Satan answered: "I have been walking here and there, roaming around the earth (meaning empowering the flesh against the Word of God). Then the Lord asked: "Did you notice my servant Job? (As an example of being servant of God. Satan was a servant of God but he failed in his duties). The Lord continues: "There is no one on earth as faithful and good as he is (He was the only one, not even Job's family). He worships Me and is careful not to do anything evil (meaning that Job applied the Word of God in his life with so much care in the understanding). Satan replied (according to his nature and understanding), "Would Job worship you if he got nothing out of it (a doctrine of our days)? ... You bless everything he does ... But now suppose You take away everything he has -he will curse you to Your Face (like Satan did when God took away everything from him the day in which he rebelled against Him). The Lord said to Satan: "All right. Everything he has is (now) in your power, but you must not take his life." So Satan left.
Job, under test, suffered a total disaster -he lost all of his children and property and was afflicted with a repulsive disease. Through the Prophet Ezekiel, God pointed to Job as an example of Righteousness. His patient endurance of suffering (not in the way that many doctrines portrait the physical suffering of the Christians, it is meant for the right application of the Word of God, the true understanding of His Laws, given the fact that Satan's job is to deceive the meaning of it, like he did with Eve).
God's affection and mercy is magnified in Job's happy outcome. At the end of his faithful course under test God constituted Job a Priest for his 3 companions who had contended with him (representing the Word of God) and God restored Job to his former spiritual status. He again had a fine family and double the wealth he had previously possessed (a symbolic way of Christ' suffering and the restoring of his kingdom and the rights of His Primogeniture).