First: Satan’s role in deviating and misguiding man is confined to tempting him. Second: Progress and development can only take place when there are opposite and conflicting forces, and therefore the creation of such a being in the Nezame Ahsan (perfect world system) is not considered in vain, but rather a manifestation of Allah’s mercy and pure goodness.
First: Allah did not create Satan as Satan. Proof for such a claim would be that he accompanied the angels and the worshippers for many years (six thousand years), but later on he took the path of disobedience by his own free will and was distanced from Allah’s mercy.
Second: The existence of Satan is not harmful for believers and those who are determined to take the path of truth, instead it can help them to progress, develop and reach perfection; because progress, improvement and development can only take place when there are opposite forces.
The only role Satan plays in this world is the role of tempting people; meaning that he only calls people to take the wrong path. Allah has not granted him control over other beings or the authority to exert influence on souls without them choosing to obey him. The Almighty says in the Quran: “ان لیس له سلطان علی الذین آمنوا و علی ربهم یتوکلون” (Indeed he does not have any authority over those who have faith and put their trust in their Lord.) It is for this reason that when a group of people go to Satan on the Day of Judgment because of misleading them, Satan argues that: “...و ما کان لی علیکم من سلطان الاّ ان دعوتکم...” (I had no authority over you, except that I called you and you responded to me.)
The teachings of the Quran show that Satan’s role in misleading man is confined to tempting him and he never forces one to go astray; because man is called by two calls, the call of Allah and the call of Satan and it is man that freely decides which one he will follow. However, Satan does have authority and control over people that, through their free will, follow his call, carry out his demands and think of him as their example, and he will destroy their souls.
“...انما سلطانه علی الذین یتولونه” (His authority is only over those who befriend him and those who make him a partner [of Allah]...)
For more information, you can refer to the following topics:
Satan and death, Question 398 (website: 849); Satan’s weeping, Question 762 (website: 805).