There are a few ways that the theme of guilt is conveyed in Macbeth. Perhaps one example that is overlooked when it comes to illustrating guilt is Lady Macbeth's quote:
Come, you spirits
That tend on mortal thoughts, unsex me here,
And fill me, from the crown to the toe, (I.v. 40-42)
Lady Macbeth feels guilty that she is not a man. During the play, gender plays an important role. Lady Macbeth thinks that Macbeth does not have the backbone to do what needs to be done to gain the crown. So, she asks the spirits to "unsex" her so that she can become male so as to gain the crown; something she does not think her husband is really man enough to do.
Therefore, Lady Macbeth feels guilt in the fact that she was not born male given she has the male mindset needed to gain what she believes Macbeth cannot.
Guilt is an important theme because it lessens Macbeth’s drive and ambition and insensitivity. Guilt brings balance to his brutality which allows the reader to identify with him in spite of his tyranny.
Macbeth: Guilt also stops Macbeth from killing Duncan. He feels guilty before he kills him and is uncertain of his plan. Lady Macbeth calls him a coward and persuades him to kill Duncan as planned. After he carries out his plans, he is overwhelmed with a sense of guilt and thoughts of damnation. He has visions of a dagger leading him to Duncan’s room, and and begins to hear voices.
Lady Macbeth’s Guilt- Lady Macbeth also feels guilt. She is the driving force behind Macbeth committing acts of murder and becomes overtaken by guilt. Guilt is evidenced when she starts sleepwalking and talking about having blood on her hands. At the end of the play, guilt has consumed her to the point of an apparent suicide.