Ambition as a destructive force
Macbeth's ambition is the engine of the entire play. It does not build anything. It dismantles everything he has, including his marriage, his peace of mind, his friendships, and his life. Shakespeare shows ambition working like a trap: the more Macbeth grabs, the less he actually has.
Guilt and psychological collapse
Neither Macbeth nor Lady Macbeth can escape what they have done. Macbeth hallucinates daggers and ghosts. Lady Macbeth sleepwalks and relives the murders. The play treats guilt as something that accumulates and eventually breaks the person carrying it.
Appearance versus reality
Almost nothing in this play is what it looks like on the surface. The witches' prophecies sound like protection but contain fatal loopholes. Macbeth performs loyalty while planning murder. Lady Macbeth performs composure while falling apart inside. Scotland looks stable under Macbeth and is rotting.
The corrupting nature of power
Macbeth before the crown is a man with a conscience who has to be talked into murder. Macbeth after the crown orders massacres without hesitation. Power does not reveal a better version of him. It removes the parts of him that were holding the worst impulses back.
Fate versus free will
The witches predict the future, but they do not force anyone's hand. Macbeth chooses to act on the prophecies. He chooses each murder. The play keeps this tension alive: the outcome may have been fated, but Macbeth's choices are still his own, and Shakespeare holds him responsible for them.