The Trumpet is blown and those in the heavens and those in the earth swoon away, except those Allah wills. Then it is blown a second time and at once they stand upright, looking on. And the earth shines with the Pure Light of its Lord; the Book is put in place; the Prophets and witnesses are brought; it is decided between them with the truth; and they are not wronged. Every self is repaid in full for what it did. He knows best what they are doing. (Surat az-Zumar, 68-70)
All who have ever lived on earth are resurrected on the Day of Judgment. The moment of resurrection is a perplexing one for unbelievers. Allah relates the fearful and bewildered conversations among unbelievers at the moment of resurrection in the Qur'an as follows:
They will say, "Alas for us! Who has raised us from our resting-place? This is what the All-Merciful promised us. The Messengers were telling the truth." (Surah Ya Sin, 52)
And the True Promise is very close, the eyes of those who were unbelievers will be transfixed: "Alas for us! We were unmindful of this! No, rather we were definitely wrongdoers." (Surat al-Anbiya, 97)
The phrase "Alas for us" is an expression of the great panic, fear and regret of unbelievers. At the moment they are resurrected, they realize that those who warned them against the hereafter were right and truthful. Much to their detriment, they are now aware that other warnings will surface one after another. Right now, with no possibility to escape, they will be dragged to this torment, which they never considered as real before.
After rising from the dead, unbelievers will be brought to stand before Allah. Then they will be called to account for what they did in the world and judgment will be made accordingly. For this purpose, they are brought into the Presence of Allah with all those other arrogant people who transgressed against the limits set by Allah.
The Day the Trumpet is blown and you come in droves. (Surat an-Naba, 18)
On the judgment day, unbelievers will come to understand that no other action is more important than earning the consent of Allah and avoiding His wrath. This is also stated in a hadith of the Prophet (saas) in which he gave the example of an unbeliever questioned on the judgment day: An unbeliever will be brought on the Day of Resurrection and will be asked. "Suppose you had as much as gold as to fill the earth, would you offer it to ransom yourself?" He will reply: "Yes". Then it will be said to him, "You were asked for something easier than that [to join none in worship with Allah (i.e. to accept Islam, but you refused)]" (Bukhari) Their failure to have grasped this fact in the world, where the signs of Allah's power and existence were obvious, intensifies their regret.
The Day when a wrongdoer will bite his hands and say, "Alas for me! If only I had gone the way of the Messenger! Alas for me! If only I had not taken so-and-so for a friend! He led me astray from the Reminder after it came to me." Evil always leaves man in the lurch. (Surat al-Furqan, 27-29)
On the Day of Judgment, unbelievers will be so occupied with their own troubles that they turn a blind eye to the calls of their own children, spouses, mothers, and fathers. In the Qur'an, this is described as follows:
When the Deafening Blast comes, the Day a man will flee from his brother and his mother and his father, and his wife and his children: on that Day every man among them will have concerns enough of his own. (Surah Abasa, 33-37)
The concept of lineage loses its importance. From then on, the only thing that matters is to be saved from the penalty of Allah. This is so important that, in order to be saved from this state, unbelievers even offer to sacrifice their own sons, spouses, brothers, etc.
On the Day the sky is like molten brass and the mountains like tufts of colored wool. No good friend will ask about his friend even though they can see each other. An evildoer will wish he could ransom himself from the punishment of that Day, by means of his sons, or his wife or his brother or his family who sheltered him or everyone else on earth, if that only meant that he could save himself. (Surat al-Ma'arij, 8-14)
Surely, these efforts of unbelievers bring no results. The main target of unbelievers in the worldly life was amassing a fortune, making a career, or having sons. They spent all their lives to attain these goals. However, on the Day of Judgment, they grasp that all these concepts are not precious at all. Judgment Day is the time when unbelievers will desire to vanish. For believers, however, it is the time zealously and joyfully awaited for. Allah describes these moments in His verses as follows:
That Day some faces will be radiant, laughing, rejoicing. That Day some faces will be dust-covered, overcast with gloom. Those are the dissolute unbelievers." (Surah Abasa, 38-42)
On the Day of Reckoning, the most precious valuables one possesses are the righteous deeds purely done to earn the good pleasure of Allah. However, unbelievers have never striven for this treasure, which would bring them eternal salvation. Not a single good deed or blessing they have to present to Allah on that day. Having no faith in Allah, all their righteous efforts will have been wasted. Allah states this fact as follows:
Say: "Shall I inform you of the greatest losers in their actions? People whose efforts in the life of the world are misguided while they suppose that they are doing good." Those are the people who reject their Lord's Signs and the meeting with Him. Their actions will come to nothing and, on the Day of Resurrection, We will not assign them any weight." (Surat al-Kahf, 103-105)
Those who denied the religion (deen) and harbored doubts about the existence of the Day of Judgment, did not feel the necessity to get prepared for this approaching day. For a lifetime, they occupied themselves with amassing wealth and following their vain desires. Now they confront a regret they will never be free of. Allah states this in the Qur'an in this way:
They will say, "Alas for us! This is the Day of Reckoning!" This is the Day of Decision you used to deny. (Surat as-Saffat, 20-21)
Furthermore, unbelievers will find all the unscrupulous, ungrateful and evil deeds that they committed in the world discovered in the Presence of Allah. They will personally bear witness to the sins they committed. Allah describes this in the Qur'an as follows:
...They will be paraded before your Lord in ranks: "You have come to Us just as We created you at first. Yes indeed! Even though you claimed that We would not fix a time with you." The Book will be set in place and you will see the evildoers fearful of what is in it. They will say, "Alas for us! What is this Book which does not pass over any action, small or great, without recording it?" They will find there everything they did and your Lord will not wrong anyone at all. (Surat al-Kahf, 48-49)
That Day people will emerge segregated to see the results of their actions. Whoever does an atom's weight of good will see it. Whoever does an atom's weight of evil will see it. (Surat az-Zilzal, 6-8)
As Allah relates in the Qur'an, then comes the time for unbelievers to see their records. Believers receive their records from their right side, whilst unbelievers from left. From the moment the angels of death took their souls, unbelievers were subjected to an unending suffering. The moment they receive their records is another suffering. They avoid looking at the crimes they perpetrated and wish to vanish. Allah describes this in the verses as follows:
But as for him who is given his Book in his left hand, he will say, "If only I had not been given my Book and had not known about my Reckoning! If only death had really been the end! My wealth has been of no use to me. My power has vanished." (Surat an-Naba, 25-29)
... On the Day when a man will see what he has done, and the unbeliever will say, "Oh, if only I were dust!" (Surat an-Naba, 40)
But as for him who is given his Book behind his back, he will cry out for destruction but will be roasted in a Searing Blaze. He used to be joyful in his family. He thought that he was never going to return. But in fact his Lord was always watching him! (Surat al-Inshiqaq, 10-15)
Witnessing these scenes, unbelievers understand the opportunity that they missed in the world and feel a most severe regret. Adding to their regret, they see and observe the blissful life of believers in paradise. Because previously, they were invited to truth by believers but they arrogantly refused and turned a deaf ear to them. But now a "just balance" (Surat al-Anbiya': 47) is set. People are led to hell or paradise, based on their records. On the Day of Judgment, unbelievers see where they are heading for. Upon this, fear overtakes them:
You will see the wrongdoers afraid of what they have earned, when it is about to land right on top of them. (Surat ash-Shura, 22)
The justice of Allah prevails and it entails the fairest rewarding and punishment:
We will set up the Just Balance on the Day of Resurrection and no self will be wronged in any way. Even if it is no more than the weight of a grain of mustard-seed, We will produce it. We are sufficient as a Reckoner. (Surat al-Anbiya, 47)
This process is easy for believers. However, it proves to be difficult and very painful for unbelievers. They are questioned for every each blessing Allah granted them in the world. They give an account of every each moment of their lives: about their failure to comply with the commands of Allah; their ungrateful attitudes; their inner rebellious thoughts and insults; the warnings that they ignored. However the insincere excuses they used to put forth in the world are no more acceptable. Allah describes the situation unbelievers confront on that day in the verses below:
On that Day, woe to the deniers! This is the Day they will not say a single word, nor will they be allowed to offer any excuses. On that Day, woe to the deniers! "This is the Day of Decision. We have gathered you and the earlier peoples. So if you have a ploy, use it against Me now!" On that Day, woe to the deniers! (Surat al-Mursalat, 34-40)
Those unbelievers with no good deeds to present to Allah "will know what it has made ready" (Surat at-Takwir: 14) for them. Allah describes this place of torment as a "bottomless pit" in the Qur'an:
As for him whose balance is heavy, he will have a most pleasant life. But as for him whose balance is light, his motherland is Hawiya (Pit). And what will convey to you what that is? A raging Fire! . (Surat al-Qari'a, 6 –11)
These are important to grasp the intensity of the regret unbelievers would experience on the Day of Judgment. The Day of Judgment is too late for one to feel regret. If one fully understands what is being told here and loses no time in engaging in good deeds, then he may hope for a "heavy balance (of good deeds)." Only such an endeavor will save one from great regret.