Q: The Satan was a monotheist and now also he is a monotheist How then would this verse not apply to him?
إِنَّ اللَّهَ لَا يَغْفِرُ أَنْ يُشْرَكَ بِهِ وَيَغْفِرُ مَا دُونَ ذَٰلِكَ لِمَنْ يَشَاءُ ۚ وَمَنْ يُشْرِكْ بِاللَّهِ فَقَدْ ضَلَّ ضَلَالًا بَعِيدًا
"Surely Allah does not forgive that anything should be associated with Him, and He forgives what is besides this to whom He pleases ..." (An- Nisa, 4: 1 16)
A: It is true that Satan was not a polytheist in the beginning, because polytheism means to take someone as a partner of God in His creation, obedience or worship. Such polytheism was not there in the devil; but disbelief is worse than polytheism, because it is to give up the obedience of Almighty Allah due to enmity or ego; and according to Quran, Satan was a disbeliever, which is worse than being a polytheist.
أَبَىٰ وَاسْتَكْبَرَ وَكَانَ مِنَ الْكَافِرِينَ
"…He refused and he was proud, and he was one of the unbelievers." (Al Baqarah, 2:34)
And in Al-Kafi it is narrated from Zurarah that Imam Baqir (a.s.) said: By Allah, disbelief is older than polytheism and so also dirtier and more serious. Then the Imam recalled the disbelief of lblis when Allah ordered him to prostrate before Adam, but he disobeyed.7Thus infidelity is graver than polytheism.
Imam Sadiq (a.s.) was asked which of the two: disbelief and polytheism is older? He replied that disbelief is older, because Iblis was the first to become a disbeliever and his disbelief was not like polytheism, because he did not invite others to worship anyone other than God and, in fact, thereafter he extended such an invitation and became a polytheist.8
It is clear from the tradition that Satan is both a disbeliever as well as a polytheist, but his disbelief is due to the fact that he disobeyed God's command and in other words denied the Lordship, divinity and His right to be obeyed and worshipped. In a tradition of Imam Ridha’ (a.s.) such disbelief is named as ultimate disbelief.
But the cursed one's being a polytheist is because he became damned and engaged himself in misguiding human beings. He called to polytheism; and things like idol-worship etc. are his inventions only. It is obvious that invention of polytheism and trapping people into it is a thousand times worse than his personal polytheism so the cursed one is the first disbeliever and the chief of the polytheists.
This summary of this question is that the Almighty Allah has said in Quran that Allah would not forgive one who associates others with Him and, excepting the sin of polytheism, He would forgive the sins of whomsoever He wishes.
Therefore, since Satan, in the beginning, only refused to prostrate for Adam, he had not associated anyone with God, that is, he had not committed polytheism; his sin is worth forgiveness.
The gist of the reply is that Satan was a disbeliever from the beginning and thereafter led man to disbelief and he also became a polytheist and encouraged people to various kinds of polytheism. From the very beginning till now, he has no faith in Allah. If it is said that Satan had accepted God and had believed in the Creator of the universe and that he only refused to obey His Commandment, then we reply that only to testify that there is a creator of the world of existence is not faith in Allah.
Faith in God means one must accept Allah as the creator, nourisher and upbringer of oneself and of every particle in the universe and also one must believe that he and all the things of the world are due to Allah only, and he should not consider himself and others as existing by themselves. He must also regard only Allah as worthy of worship. Thus he should surrender before only one God and to fear Him and to humble before Him. Only such a person is a believer in Allah.
Thus one who considers himself independent, like lblis, crosses the limits of being His servant and shows his own opinion, rather who considers his own opinion higher than the command of God and thus shows pride against God, has doubtlessly become a denier of God's Godship and Lordship and of His being the only deity worth worship. Such a person will not get a place except in Hell.
إِنَّ الَّذِينَ يَسْتَكْبِرُونَ عَنْ عِبَادَتِي سَيَدْخُلُونَ جَهَنَّمَ دَاخِرِينَ {60}
"...surely those who are too proud for My service shall soon enter Hell abased. "
(Al- Ghafir, 40:60)
Sayyid Abdul Husayn Dastghaib