Question: "You have said that some people will receive mercy in the final judgment while others will receive justice. But, what if those that have wronged you are forgiven? Won’t you not receive justice, then? And, what about your own forgiveness and those you have transgressed against – will they not receive justice? Real justice is a restoration of the victim. And, that could be retributive as opposed to restitution or some other such thing, but not just any retribution is okay in such a transaction. It is not enough that “they suffered, too”. They have to suffer a precise measure of consequences for abusing you while you are vindicated and made whole again. So how can a person who has harmed another be saved and receive mercy if perfect justice is done in the final judgment?”
I will answer your question with quotations from a portion of the greatest novel ever written: The Brothers Karamazov, by Feodor Dostoyevsky (a devout Orthodox Christian, and one might say... a great lay theologian):
In the novel, you have three brothers. Ivan, the second oldest brother, is an atheist, while the youngest brother Alexei (Alyosha) is a novice monk, and a pious believer. In one conversation, Ivan presents his brother with a problem along the lines of your question. He tells a story, which in fact was based on an actual incident:
“One picture, only one more, because it's so curious, so characteristic, and I have only just read it in some collection of Russian antiquities. I've forgotten the name. I must look it up. It was in the darkest days of serfdom at the beginning of the century, and long live the Liberator of the People! There was in those days a general of aristocratic connections, the owner of great estates, one of those men—somewhat exceptional, I believe, even then—who, retiring from the service into a life of leisure, are convinced that they've earned absolute power over the lives of their subjects. There were such men then. So our general, settled on his property of two thousand souls, lives in pomp, and domineers over his poor neighbors as though they were dependents and buffoons. He has kennels of hundreds of hounds and nearly a hundred dog-boys—all mounted, and in uniform. One day a serf-boy, a little child of eight, threw a stone in play and hurt the paw of the general's favorite hound. ‘Why is my favorite dog lame?’ He is told that the boy threw a stone that hurt the dog's paw. ‘So you did it.’ The general looked the child up and down. ‘Take him.’ He was taken—taken from his mother and kept shut up all night. Early that morning the general comes out on horseback, with the hounds, his dependents, dog-boys, and huntsmen, all mounted around him in full hunting parade. The servants are summoned for their edification, and in front of them all stands the mother of the child. The child is brought from the lock-up. It's a gloomy, cold, foggy autumn day, a capital day for hunting. The general orders the child to be undressed; the child is stripped naked. He shivers, numb with terror, not daring to cry.... ‘Make him run,’ commands the general. ‘Run! run!’ shout the dog-boys. The boy runs.... ‘At him!’ yells the general, and he sets the whole pack of hounds on the child. The hounds catch him, and tear him to pieces before his mother's eyes!... I believe the general was afterwards declared incapable of administering his estates. Well—what did he deserve? To be shot? To be shot for the satisfaction of our moral feelings? Speak, Alyosha!”
[After a bit of back and forth, Ivan closes with this argument:]
“Listen! I took the case of children only to make my case clearer. Of the other tears of humanity with which the earth is soaked from its crust to its center, I will say nothing. I have narrowed my subject on purpose. I am a bug, and I recognize in all humility that I cannot understand why the world is arranged as it is. Men are themselves to blame, I suppose; they were given paradise, they wanted freedom, and stole fire from heaven, though they knew they would become unhappy, so there is no need to pity them. With my pitiful, earthly, Euclidian understanding, all I know is that there is suffering and that there are none guilty; that cause follows effect, simply and directly; that everything flows and finds its level—but that's only Euclidian nonsense, I know that, and I can't consent to live by it! What comfort is it to me that there are none guilty and that cause follows effect simply and directly, and that I know it?—I must have justice, or I will destroy myself. And not justice in some remote infinite time and space, but here on earth, and that I could see myself. I have believed in it. I want to see it, and if I am dead by then, let me rise again, for if it all happens without me, it will be too unfair. Surely I haven't suffered, simply that I, my crimes and my sufferings, may manure the soil of the future harmony for somebody else. I want to see with my own eyes the hind lie down with the lion and the victim rise up and embrace his murderer. I want to be there when every one suddenly understands what it has all been for. All the religions of the world are built on this longing, and I am a believer. But then there are the children, and what am I to do about them? That's a question I can't answer. For the hundredth time I repeat, there are numbers of questions, but I've only taken the children, because in their case what I mean is so unanswerably clear. Listen! If all must suffer to pay for the eternal harmony, what have children to do with it, tell me, please? It's beyond all comprehension why they should suffer, and why they should pay for the harmony. Why should they, too, furnish material to enrich the soil for the harmony of the future? I understand solidarity in sin among men. I understand solidarity in retribution, too; but there can be no such solidarity with children. And if it is really true that they must share responsibility for all their fathers' crimes, such a truth is not of this world and is beyond my comprehension. Some jester will say, perhaps, that the child would have grown up and have sinned, but you see he didn't grow up, he was torn to pieces by the dogs, at eight years old. Oh, Alyosha, I am not blaspheming! I understand, of course, what an upheaval of the universe it will be, when everything in heaven and earth blends in one hymn of praise and everything that lives and has lived cries aloud: ‘Thou art just, O Lord, for Thy ways are revealed.’ When the mother embraces the fiend who threw her child to the dogs, and all three cry aloud with tears, ‘Thou art just, O Lord!’ then, of course, the crown of knowledge will be reached and all will be made clear. But what pulls me up here is that I can't accept that harmony. And while I am on earth, I make haste to take my own measures. You see, Alyosha, perhaps it really may happen that if I live to that moment, or rise again to see it, I, too, perhaps, may cry aloud with the rest, looking at the mother embracing the child's torturer, ‘Thou art just, O Lord!’ but I don't want to cry aloud then. While there is still time, I hasten to protect myself, and so I renounce the higher harmony altogether. It's not worth the tears of that one tortured child who beat itself on the breast with its little fist and prayed in its stinking outhouse, with its unexpiated tears to ‘dear, kind God’! It's not worth it, because those tears are unatoned for. They must be atoned for, or there can be no harmony. But how? How are you going to atone for them? Is it possible? By their being avenged? But what do I care for avenging them? What do I care for a hell for oppressors? What good can hell do, since those children have already been tortured? And what becomes of harmony, if there is hell? I want to forgive. I want to embrace. I don't want more suffering. And if the sufferings of children go to swell the sum of sufferings which was necessary to pay for truth, then I protest that the truth is not worth such a price. I don't want the mother to embrace the oppressor who threw her son to the dogs! She dare not forgive him! Let her forgive him for herself, if she will, let her forgive the torturer for the immeasurable suffering of her mother's heart. But the sufferings of her tortured child she has no right to forgive; she dare not forgive the torturer, even if the child were to forgive him! And if that is so, if they dare not forgive, what becomes of harmony? Is there in the whole world a being who would have the right to forgive and could forgive? I don't want harmony. From love for humanity I don't want it. I would rather be left with the unavenged suffering. I would rather remain with my unavenged suffering and unsatisfied indignation, even if I were wrong. Besides, too high a price is asked for harmony; it's beyond our means to pay so much to enter on it. And so I hasten to give back my entrance ticket, and if I am an honest man I am bound to give it back as soon as possible. And that I am doing. It's not God that I don't accept, Alyosha, only I most respectfully return Him the ticket.”
“That's rebellion,” murmured Alyosha, looking down.
“Rebellion? I am sorry you call it that,” said Ivan earnestly. “One can hardly live in rebellion, and I want to live. Tell me yourself, I challenge you—answer. Imagine that you are creating a fabric of human destiny with the object of making men happy in the end, giving them peace and rest at last, but that it was essential and inevitable to torture to death only one tiny creature—that baby beating its breast with its fist, for instance—and to found that edifice on its unavenged tears, would you consent to be the architect on those conditions? Tell me, and tell the truth.”
“No, I wouldn't consent,” said Alyosha softly.
“And can you admit the idea that men for whom you are building it would agree to accept their happiness on the foundation of the unexpiated blood of a little victim? And accepting it would remain happy for ever?”
“No, I can't admit it. Brother,” said Alyosha suddenly, with flashing eyes, “you said just now, is there a being in the whole world who would have the right to forgive and could forgive? But there is a Being and He can forgive everything, all and for all, because He gave His innocent blood for all and everything. You have forgotten Him, and on Him is built the edifice, and it is to Him they cry aloud, ‘Thou art just, O Lord, for Thy ways are revealed!’ ”
Christ was the greatest of innocent sufferers, and he has the power to forgive, even those who have committed the most horrible of crimes. The parable of the unforgiving servant (Matthew 18:21-35) makes clear that the debts that men owe to one another for their offenses are relatively minor in comparison with the debt we owe God. God is our creator, and to Him we owe our very existence, and yet we sin against Him. Our fellow men are finite creatures, and while we sin against each other, the degree of the offense is small because we are not offending our great benefactor, but fellow creatures. It is our Creator that we owe the real debt to, and it is He that has the power to forgive great sinners, and also the power to not only make those who have suffered whole, but to bestow upon them infinite blessings that even they do not deserve.
So those who repent of their sins, and accept God's forgiveness and grace will receive mercy on the day of judgment. Those reject God's grace will get God's justice on the day of judgment. No one will receive injustice on the day of judgment.