إِنَّ الَّذِينَ كَفَرُواْ سَوَاءٌ عَلَيْهِمْ أَأَنذَرْتَهُمْ أَمْ لَمْ تُنذِرْهُمْ لاَ يُؤْمِنُونَ {6} خَتَمَ اللَّهُ عَلَى قُلُوبِهِمْ وَعَلَى سَمْعِهِمْ وَعَلَى أَبْصَارِهِمْ غِشَاوَةٌ وَلَهُمْ عَذَابٌ عَظِيمٌ {7}
{6} Surely those who disbelieve, alike is it to them whether you warn them or do not warn them, they will not believe. {7} Allah has set a seal upon their hearts and upon their hearing; and there is a covering over their eyes; and for them is a great punishment.

Commentary
QUR’AN: Surely those who disbelieve… will not believe:

They were the people who obstinately clung to rejection of faith and in whose hearts disbelief had established deep roots. This may be inferred from the fact that warning them and not warning them was all alike to them; they would not move from their obduracy. Probably it refers to the disbeliever of Quraysh, who were the bitterest enemies of Islam and who did try their utmost to extinguish the light of faith; they persisted stubbornly in their enmity until Allah destroyed them in Badr and other battles. The sentence, “alike is it to them whether you warn them or do not warn them, they will not believe”, strengthens this interpretation; because it could not be applied to all the disbeliever of the world – otherwise the door of guidance would be closed. Also, this same sentence has come in Chapter of Ya Sin (36:10) which is a Meccan chapter. Then it appears in this chapter that is the first chapter revealed at Medina. (It was revealed before the battle of Badr.) Therefore, more probably this verse also refers to the same Meccan group. In other places too the same explanation may be given to the word, “those who disbelieve”, unless there is a reason to the contrary.

Likewise, wherever the word, “those who believe”, has been used in the Qur’an it refers to the first and early Muslims – unless there is any reason to believe otherwise. This style of address was reserved for them as a protocol of honor.

QUR’AN: Allah has set a seal… great punishment:

Allah has ascribed the sealing to His own action, but the covering over their eyes is attributed to their own selves. It shows that they had put a curtain on their souls against the light of truth – it was their own choice. Then, after their sins and disbelief, Allah put another curtain or seal over their souls. Their disbelief and misdeeds thus fall between two curtains – the first from themselves, the second from Allah.

Its further explanation will be given under 2:26; SurelyAllah is not ashamed to set forth any parable – that of a gnator any thing above that …

Disbelief, like belief, has various degrees and ranks; and its effects also vary, like those of belief.

Traditions
az-Zubayri says that he said to as-Sadiq (a.s.): “Tell me how many ways of al-kufr (disbelief, infidelity, to cover) are there according to the Book of Allah? Mighty and Great is He! He (the lmam) said: ‘Disbelief, according to the Book of Allah, is of five types. There is the disbelief of denial (and denial is of two kinds), and the disbelief by neglecting what Allah has ordered, and the disbelief of disavowal, and the ingratitude. As for the disbelief of denial, it is denial of the Lordship; it is the talk of those who say: “there is no Lord (i.e. Creator), nor any Garden nor Fire .” It is the word of two groups of disbeliever who are called atheists. And they are those who say: “nothing destroys us but time” (45: 24). It is a religion invented by them as it seemed good to them, but they have no proof to support their view. That is why Allah has said (about them): And they have no knowledge of that; they only conjecture (ibid.), that it is in reality as they say. And He also said: Surely those who disbelieve, alike is it to them whether you warnthem or do not warn them, they will not believe.'” (al-Kafi)

And as for the second kind, it is the denial after knowing; it means that the denier denies (the existence of God), but he knows (very well) that He is the truth, and he is convinced of it (in his heart). And Allah has said (about such people): And theydenied them unjustly and proudly while their soul had been convinced of them (27:14); …and aforetime they used to prayfor victory against those who disbelieved, but when there came tothem that which they did recognize (i.e. the Prophet) they disbelieved in him; so Allah’s curse is on the unbelievers (2: 89).

So this is the explanation of the two kinds of denial.

And the third way of disbelief is ingratitude to the bounties (of Allah); and it is as Allah says quoting (the Prophet) Sulayman: “This is of the grace of my Lord that He may try me whether I am grateful or ungrateful; and whoever is grateful, he is grateful only for his own self and whoever is ungrateful, then surely my Lord is Self-sufficient, Honored” (27:40); If you are grateful, I would certainly give you more, and if you are ungrateful, My chastisement is truly severe (14:7). Therefore remember Me, I will remember you, and be thankful to Me, and do not be ungrateful to Me (2:152). (In all these verses Allah has used the word al-kufr disbelief, to denote ungratefulness, and ingratitude.)

And the fourth way of disbelief is leaving out or neglecting what Allah has ordered to do. It is as Allah says: And when We made a covenant with you: You shall not shed your blood and you shall not turn your people out of your cities; then you gave a promise while you witnessed. Yet you it is who slay your people and turn a party from among you out of their homes, backing each other up against them unlawfully and exceeding the limits; and if they should come to you as captives, you would ransom them – while their very turning out was unlawful for you. Do you then believe in a part of the book and disbelieve in the other? (2:84-85). In this verse Allah has charged them with disbelief because they did not follow the commandment of Allah; (it should be noted that) Allah has (in this very verse) linked them to belief, yet He did not accept it from them and it did not benefit them before Allah. So Allah (further) said: What thenis the reward of such among you as do this but disgrace in thelife of this world, and on the day of resurrection they shall besent back to the most grievous chastisement, and Allah is not atall heedless of what you do (ibid.)

And the fifth way of disbelief is disavowal. It is as Allah says, quoting lbrahim (a.s.) ..”.we renounce you, and enmity and hatred have appeared between us and you for ever until you believe in Allah alone” (60:4), that is, we disavow and repudiate you. And He says, describing Iblis and his disowning his friends from mankind on the Day of Resurrection: ..”.surely I disbelieved in your associating me (with Allah) before” (14:22). And also He says: And he said: “You have only taken for yourselvesidols besides Allah by way of friendship between you in theworld’s life, then on the resurrection day some of you shall denyothers, and some of you shall curse others… (29: 25), that is, some of you shall dissociate from others.

The author says: This tradition confirms what we have previously mentioned that disbelief has many grades and ranks.

Source : shiasource