First, Macbeth is just a good story. An honorable man is tempted into committing the unspeakable: murdering his king, his kinsman, and his guest. But Shakespeare's greatness lies in his ability to understand human nature. What separates Macbeth from villains such as Iago is his guilt. In fact, before the murder, Macbeth knows all the reasons that he should not kill Duncan. He knows that it is only his "vaulting ambition" that overrides his scruples, but notice that before he goes in to kill Duncan that he is almost delirious, seeing a bloody dagger in the air. This murder is not easy for him.
His last words before killing Duncan refer to the bell that "summons thee to heaven or to hell." This line is an especially important line because Macbeth does believe in the afterlife, and he knows that he is trading his soul for the kingship.
After the murder, Macbeth is filled with regret and remorse. He cannot say "Amen" ; he wishes that the knocking at the gate could awaken Duncan. He feels as if he will turn the green sea red when he tries to wash the blood off his hands. Macbeth is not a psychopath; he is deeply remorseful for what he did. And this remorse keeps him from sleeping at night.
But he has crossed the line into the world of evil, and he feels as if there is no return. He has already lost his "eternal jewel," his soul, so he becomes more and more desparate to make sure that this sacrifice has been worth it. To remain safely king, he feels he must continue to kill; this conclusion leads to the murder of Banquo and MacDuff's family. But these murders affect his conscience as well. Deeply. He sees the ghost of Banquo at the banquet, and he reacts with horror. His subconscious guilt cannot be suppressed. When he faces Macduff in the final act, he does not want to kill him: "My soul is too much charged/With blood of thine already."
Macbeth is a good man who commits evil acts. And in so doing, loses everything: his peace and contentment in the here and now as well as his soul, and he is acutely aware of these consequences throughout the play. Through Macbeth,Shakespeare shows the overwhelming effects of guilt.
Shakespeare's Macbeth presents several facets of suffering brought on by guilt. Lady Macbeth presents the most complex study of guilt, though, so I'll center on her.
At first glance, she seems completely free of guilt early in the play. She is ruthless and aggressive and, in fact, worries that her husband will not be able to follow through with an assassination attempt. After the murder, when her husband shows signs of guilty feelings (hearing voices and obsessing about the victim's blood on his hands), she dismisses these qualms and seems not to be at all bothered.
Yet, she is not quite as hardened to guilt as she seems. Her speech in Act 1.5 (in which she asks to be unsexed--to be made more like a man) is often quoted as a sign of her ruthlessness. And it is. Yet, the fact that she feels the need to ask the spirits to unsex her, to thicken her blood so softer emotions like pity and kindness won't reach her mind, and to exchange her breast milk for poison, suggests that she has her doubts. In other words, she is worried, too, that she won't be able to go through with it, as well as that her husband won't be able to go through with it.
As the play continues and her guilt, apparently, deepens, it is made known in the famous sleepwalking scene (Act 1.5). Asleep, Lady Macbeth's conscious restraints that would normally protect her from incriminating herself are inactive, and she reveals the heinous acts she has caused, directly (Duncan's murder) or indirectly (the murders of Banquo and Macduff's wife). Rubbing her hands, she displays O.C.D.-like symptoms as she obsesses over nonexistent blood on her hands--Duncan's blood.
Soon, Lady Macbeth commits suicide.
In the course of the play, then, Lady Macbeth is doomed by her guilt: destroyed by that which she earlier worried would doom her husband from reaching his desired destiny.
In the play 'Macbeth' by William Shakespeare, it is true to say that macbeth appears tortured, but whether it is by guilt is difficult to say - and critics still argue over this point. If he is truly psychologically disturbed, then it is possible that Macbeth is psycopathic and is unable, due to past childhood experiences to feel guilt, remorse, contrition or any other emotion requiring an abiltity to empathise with others at all, let alone victims. When he says 'I am in blood stepped in so far that,should I wade no more,returning were as tedious as go o'er' (Act 3 Scene 4) it is hard to tell whether it is pity for victims or himself or fear or punishment that is driving him - it seems that any guilt is outweighed by the idea of being in a penny, in for a pound - and no going back. In that,he is culpable.
A challenging question indeed!
Macbeth, the shortest but darkest Shakespearean tragedy, is an implicit study of guilt resulted in penetration and psychosis. Fear, madness, death, and illusion or hallucination - all these are enough to prove this point.
Macbeth is a play of power-game, where the protagonist turns out to be a "butcher" driven by the force of ambition. Gluttony makes him terminate all the people whom he finds as threats to his way to the royal throne. Neither he hesitates to murder his heavenly master Duncan, the king of Scotland, nor he wavers to kill many other innocent humans. Lady Macbeth works as an instigator to push him ahead. But as it is said, crime does not spare even the criminal, so, both of them not only summon their disaster, but also bring about terrible misery for themselves. Macbeth is found many a times going through dilemma, fear and illusion because of his mental stress occurred as a consequence of his heinous deed. And then, Lady Macbeth's ambition leads herself to insomnia, insanity and death.
Guilt is the cause of marring peace in Macbeth. Macbeth's "vaulting ambition" kills his peace for good as well. In scene 2 of the second act, Macbeth, out of his guilt and stress, hears a voice crying "Sleep no more;/ Macbeth does murder sleep... Macbeth shall sleep no more"; and we find out that, sleep, which symbolises tranquility here, disappears from the lives of Macbeth and his wife in reality. Macbeth, while running after ambition, loses mental tranquility. Lady Macbeth, simultaneously, could no longer bear her guilt. It is because of the guilt she sees the hallucinatory blood in her hands which she wants to clean up, but can not. Her inability to wash the blood away symbolises her feeling that the crime she committed is also irremovable. Because of the sense of guilt, she loses her sanity and is compelled to commit suicide.
Guilt evokes different hallucinations and illusion in Macbeth. Macbeth hallucinates the ghost of Banquo in act 3, scene 4. This ghost is nothing but "the very painting of fear", an illusion created by his fear as a result of his guiltiness for murdering innocent Banquo. Besides, in the first scene of act 2, before going to murder Duncan, Macbeth sees an illusory dagger which stands for his internal fear and dilemma "proceeding from the heat-oppressed brain".
Besides, some speeches in the play like Macbeth's disability to say 'Amen' in 2.2 ('Amen' stuck in my throat), and Lady Macbeth's utterances "who would have thought the old man to have had so much blood in him", "No more o'that my lord, no more o'that", and "what's done, cannot be undone" in 5.1 expose the characters' feeling of guiltiness.
Different images like raven, bell, drum- all are indication of Macbeth's internal alarming fear and suppressing guilt.
Moreover, Lady Macbeth's death is the greatest proof of the terrible tormenting aspect of guilt. Her becoming mentally imbalanced is nothing but the consequence of her inner trauma.
Hopefully you have got some ideas and textual references through this answer.