Allah Forgave Adam and Eve for their sins after they ate from the forbidden tree. Allah forgive all of our sins as he promised if we commit Tawbah. The books of hadith are full of hadiths about how merciful Allah is. Its even one of Allah's names (The Most Merciful - الرحيم).
My question: Why didn't Allah forgive Eblees (The Devil)?
Qur'an 2:34 :
And [mention] when We said to the angels, "Prostrate before Adam"; so they prostrated, except for Iblees. He refused and was arrogant and became of the disbelievers.
Iblees was arrogant with Allah when the Almighty asked him to bow before Adam.
Qur'an 15:28-35 :
And [mention, O Muhammad], when your Lord said to the angels, "I will create a human being out of clay from an altered black mud. And when I have proportioned him and breathed into him of My [created] soul, then fall down to him in prostration." So the angels prostrated - all of them entirely, Except Iblees, he refused to be with those who prostrated. [ Allah ] said, O Iblees, what is [the matter] with you that you are not with those who prostrate?" He said, "Never would I prostrate to a human whom You created out of clay from an altered black mud." [ Allah ] said, "Then get out of it, for indeed, you are expelled. And indeed, upon you is the curse until the Day of Recompense."
From the above two references, what we see is just arrogance and kibr(Feeling of superiority) by Iblees and there was no repentance from his side. And Allah doesn't like the arrogant.
Qur'an 16:23 :
Assuredly, Allah knows what they conceal and what they declare. Indeed, He does not like the arrogant.
Moreover, he went to the extent of blaming Allah after Allah cursed him.
Qur'an 15:39-40 :
[Iblees] said, "My Lord, because You have put me in error, I will surely make [disobedience] attractive to them on earth, and I will mislead them all Except, among them, Your chosen servants."
On the other hand, (As for your question of why did Allah forgive Adam?) Adam (pbuh) after committing a mistake (Eating the forbidden fruit), repented.
Qur'an 2:37 :
Then Adam received from his Lord [some] words, and He accepted his repentance. Indeed, it is He who is the Accepting of repentance, the Merciful.
And Indeed, If Iblees had repented after committing the mistake, Allah would have forgiven him.
Qur'an 5:39 :
But whoever repents after his wrongdoing and reforms, indeed, Allah will turn to him in forgiveness. Indeed, Allah is Forgiving and Merciful.
ۚ وَاللَّهُ عَلِيمٌ حَكِيمٌ (And Allah is the All-Knower, the Wise)
Allah did not forgive Iblees simply because he did not repent. We know the story of Adam(alayhi salam) and Iblees. When Adam realized and acknowledged that he has fallen to sin, he immediately realized his mistake and repented to Allah and asked Allah to forgive him. And Allah did.
They said, "Our Lord, we have wronged ourselves, and if You do not forgive us and have mercy upon us, we will surely be among the losers." [Surat Al-'A`rāf 7:23]
And Allah accepts his repentence.
Then Adam received from his Lord [some] words, and He accepted his repentance. Indeed, it is He who is the Accepting of repentance, the Merciful. [Surat Al-Baqarah 2:37]
This applies to us as well, every human being falls into sins but the best of them is those who repent to Allah and asks for his forgiveness and Allah is ready to forgive them.
As for Iblees, I can list his transgressions.
First, he refused to obey Allah's command to bow to Adam (alayhi salam).
And We have certainly created you, [O Mankind], and given you [human] form. Then We said to the angels, "Prostrate to Adam"; so they prostrated, except for Iblees. He was not of those who prostrated. [Surat Al-'A`rāf 7:11]
Secondly, Satan said it is since he is better than Adam (Alayhi salam). Satan did not acknowledge his sin and was arrogant of his creation i.e. by saying he was better than Adam (Alayhi salam). It is not permissible to be arrogant and boastful of ones creation. One must humble himself before Allah.
[ Allah ] said, "What prevented you from prostrating when I commanded you?" [Satan] said, "I am better than him. You created me from fire and created him from clay. [Surat Al-'A`rāf 7:12]
But Satan was wrong. Fire is not better than clay. This is because clay causes growth. Plants germinate from soil and it leads to growth. However, fire is only destruction. So, clay is better than fire and Satan was wrong.
Thirdly, Satan tried to blame Allah and the divine pre-decree for his sin and mistake.
[Satan] said, "Because You have put me in error, I will surely sit in wait for them on Your straight path. [Surat Al-'A`rāf 7:16]
So Satan blames Allah of putting him in error and leading him astray. It is not permissible for one to blame the pre-decree for his sins and only when some calamity befalls him, he accepts it as pre-decree and remains patient. So, whatever sin we do is the doing of our own hands and we cannot blame it on pre-decree as Allah says (interpretation of meaning):
What comes to you of good is from Allah , but what comes to you of evil, [O man], is from yourself. And We have sent you, [O Muhammad], to the people as a messenger, and sufficient is Allah as Witness. [Surat An-Nisā' 4:79]
Since, Satan never repented and was arrogant, boastful and disputed with Allah, there is no question of forgiving. Mercy is for the one who repents.
Source: Explanation of Story of Adam and Iblees by Shaykh Salih Al Fawzaan
There are several reasons for this ...
Allah says:
وَلِلَّـهِ يَسْجُدُ مَا فِي السَّمَاوَاتِ وَمَا فِي الْأَرْضِ مِن دَابَّةٍ وَالْمَلَائِكَةُ وَهُمْ لَا يَسْتَكْبِرُونَ ﴿٤٩﴾ يَخَافُونَ رَبَّهُم مِّن فَوْقِهِمْ وَيَفْعَلُونَ مَا يُؤْمَرُونَ
All things that move on the earth and in the heavens, and the angels, bow in homage to God, and do not behave with pride. (49) They have fear of God for His power over them, and act as commanded. [An-Nahl :49-50]
Devil was arrogant and challenge against God, he said "he created me from fire and You created from clay ",so he did not repent after his sin to God is to prostrate to Adam.
The Devil Kafr but Adam did not do it.
Finally, that Adam received from his god words of any knowledge of God knows what Satan was to ask for mercy on repentance of Adam peace be upon him to God and regrets he did, while Devil was arrogant and refused to repent, how is treated them equally !!
Allah says:
فَتَلَقَّىٰ آدَمُ مِن رَّبِّهِ كَلِمَاتٍ فَتَابَ عَلَيْهِ ۚ إِنَّهُ هُوَ التَّوَّابُ الرَّحِيمُ
Then his Lord sent commands to Adam and turned towards him: Indeed He is compassionate and kind. [Al-Baqara:37]
Allah is merciful and he forgives those who make towba honestly but ebless had never made towba to allah. Allah also forgives the Muslim ummah but doesn't forgive the disbelievers. Allah is mercy Allah is forgiveness
Eblees is not a conscious intelligent being. It is an abstract conceptual definition for explaining how and why human soul became different from the souls of all other animals during its creation.
Don't take Eblees-Adam story directly. No one can actually chit-chat with and defy Allah like in that story. That story is mutashabih, which means it is symbolic, for explaining a very complex event in a very simple and condensed way.
