First and foremost, we would like to stress the fact that humans should know their enemy well so that they can protect themselves against his plans and plots.
As Muslims, we believe that Satan is an avowed enemy who spares no effort to mislead and divert humans from the right path of salvation and eternal bliss. Therefore, it is our duty to be aware of this fact and always resort to Allah and to take refuge in Him from Satan and his whispers.
Iblis (Satan) and other jinn, and humans, have free will and freedom of choice, to obey Allah or to disobey Him, as Allah says: “… Then whosoever wills, let him believe; and whosoever wills, let him disbelieve …” (18: 29)
“Verily, We showed him the way, whether he be grateful or ungrateful.” (76: 3)
Allah commanded Iblis to prostrate before Adam, but he refused and was arrogant, and was one of the unbelievers. So Allah expelled him from His mercy and cursed him until the Day of Judgment. In this regard, Almighty Allah says: “And (remember) when We said to the angels: ‘Prostrate yourselves before Adam.’ And they prostrated except Iblis (Satan), he refused and was proud and was one of the disbelievers (disobedient to Allah).” (2: 34)
“So the angels prostrated themselves, all of them together. Except Iblis (Satan) — he refused to be among the prostrators. (Allah) said: ‘O Iblis! What is your reason for not being among the prostrators?’ (Iblis) said: ‘I am not the one to prostrate myself to a human being, whom You created from dried (sounding) clay of altered mud.’ (Allah) said: ‘Then, get out from here, for verily, you are Rajim (an outcast or a cursed one).
And verily, the curse shall be upon you till the Day of Recompense ( i.e. the Day of Resurrection).” (15: 30-35)
Then Iblis asked for a respite until the Day of Resurrection, and Allah granted him that. Regarding this the Qur’an relates : “(Satan) said: ‘O my Lord! Give me then respite till the Day they (the dead) will be resurrected.’ Allah said: ‘Then verily, you are of those reprieved, till the Day of the time appointed.'” (15: 36-38)
When Iblis was certain that he is one of those who are doomed, as well as his being arrogant and being ungrateful to his Lord, he resolved to mislead whomever he could of the slaves of Allah so that they would be with him in Hell. Allah says : “(Satan) said: ‘O my Lord! Because You misled me, I shall indeed adorn the path of error for them (mankind) on the earth, and I shall mislead them all. Except Your chosen, (guided) slaves among them.'” (15: 39-40)
Therefore, he is eager to mislead and corrupt, so as to increase the numbers of his followers and worshippers among the doomed who will share his fate. Iblis knows that his destination is the Fire, and he hopes to take everyone else with him to Hell, out of envy, hatred, disbelief and stubbornness.