Betrayal and Murder
The obvious theme of Macbeth is betrayal. Betrayal, however, goes beyond Macbeth's gruesome murder of the the king.
Betrayal in Macbeth includes
(1) Macbeth and Lady Macbeth's disregard for the laws of hospitality (murdering your guest automatically diqualifies you from host of the year nominations in Shakespeare's time)
(2) Macbeth's breaking of the king-subject covenant to which he is bound
(3) Macbeth betrays Banquo, to whom he is connected by battle and by knowledge of the witches' prognostications
(4) Macbeth betrays Scotland by killing a worthy king and usurping the throne
(5) Macbeth betrays his own nature through the butchery of Macduff's family; (5) Macbeth betrays Duncan by killing one who has shown kindness toward him and granted him titles and riches.
Macbeth is not the only one guilty of betrayal in Macbeth. Lady Macbeth, in addition to her betrayal of hospitality, betrays the feminine nature to spur her and her husband to commit murder. She also betrays herself as she sleepwalks in act V. The play begins with the betrayal of Scotland by Norway and the thane of Cawdor. Macduff also betrays his own family by fleeing Scotland and leaving his family vulnerable to attack.