Allah says that these antonyms are clearly not equal, the blind and the seeing are not equal, there is a difference and a huge gap between them. Darkness and light are not equal, neither are shade and the sun's heat. By the same token, the living and the dead are not equal. This is the parable Allah makes of the believers who are the living, and the disbelievers who are the dead. This is like the Ayat:
(Is he who was dead and We gave him life and set for him a light (of belief) whereby he can walk amongst men -- like him who is in the (depths of) darkness from which he can never come out) (6:122),
(The parable of the two parties is as that of the blind and the deaf and the seer and the hearer. Are they equal when compared) (11:24) The believer sees and hears, and walks in the light upon a straight path in this world and the Hereafter, until he comes to settle in Gardens (Paradise) wherein is shade and springs. The disbeliever is blind and deaf, walking in darkness from which he cannot escape, he is lost in his misguidance in this world and the Hereafter, until he ends up in fierce hot wind and boiling water, and shadow of black smoke, neither cool nor good.
(Verily, Allah makes whom He wills to hear,) means. He guides them to listen to the proof and accept it and adhere it.
(but you cannot make hear those who are in graves.) means, `just as the dead cannot benefit from guidance and the call to truth after they have died as disbelievers and ended up in the graves, so too you cannot help these idolators who are decreed to be doomed, and you cannot guide them.'
You are only a warner means, all you have to do is to convey the Message and warn them, and Allah leaves astray whomsoever He wills and guides whomsoever He wills.
(Verily, We have sent you with the truth, a bearer of glad tidings and a warner.) means, a bearer of glad tidings to the believers and a warner to the disbelievers.
(And there never was a nation but a warner had passed among them.) means, there was never any nation among the sons of Adam but Allah sent warners to them, and left them with no excuse. This is like the Ayat:
(You are only a warner, and to every people there is a guide) (13:7).
(And verily, We have sent among every Ummah a Messenger (proclaiming): "Worship Allah, and avoid all false deities." Then of them were some whom Allah guided and of them were some upon whom the straying was justified) (16:36). And there are many similar Ayat.
(And if they deny you, those before them also denied. Their Messengers came to them with clear signs,) means, clear miracles and definitive proofs.
(and with the Scriptures,) means, the Books.
(and with the Book giving light.) means, clear and obvious.
(Then I took hold of those who disbelieved,) means, `despite all of this, they denied the Messengers and the Message they brought, so I seized them, i.e., with My punishment.'
and how terrible was My denial! means, how great and intense and terrible do you think My punishment was؟ And Allah knows best.