I would say that evil functions as a force in the play. It is a force, like good, that is available to each character and evil only manifests via the choices the characters make. In that sense, no character is inherently evil; the evil is produced in the act of choosing. Macbeth does not choose to murder Duncan, Banquo, and Macduff’s family. because he wants to be evil or because he wants to do evil things. He does so based on ambition, lust for power and the ambition and lust for power from Lady Macbeth. Macbeth was impressionable and succumbed to the influence of his wife and he was coaxed by the prophecies of the weird sisters. Macbeth ultimately made these choices. He was not forced nor fated. Their prophecies are subject to interpretation. Regardless, they were not telling Macbeth what to do nor were they casting some spell on him to induce him to commit the murders; they were suggesting possible future events. Predicting the future is quite different from influencing the future. You might say Macbeth was pressured by Lady Macbeth and seduced by the weird sisters, but in the end, it was his choice as he was not forced by anyone to commit the murders.
Burning passionate love in his heart and undying loyalty to the woman he made a pledge to til death do them part.