Evil is kind of subjective, isn't it? However, Macbeth killed his best friend (and his son), and he killed Macduff's wife and son. To me, this is the evil part. Killing Duncan was a horrible act, and possibly an evil one, but at least he had a reason. He did not have a reason to kill Macduff’s wife and son.
I would have to agree that Macbeth, being a tragic hero (having the potential for greatness but tripping over his own feet) is not evil. Isn't that why we have tragic heroes (as opposed to just villains?) Lady Mac, on the other hand (stained with blood!) has no potential in the higher order of things. She's the wife of a respected, brave, loyal and fierce general/warrior. Her destiny is what it is. Macbeth, however, could have secured his place in history as the valiant defeater of MacDonwald and savior of Scotland - but he goofed and let himself be led astray by his vaulting ambition (with the help of his not-so-better half).
I agree with Post #3. Macbeth, as with all of us, has the choice to follow the good or the evil instincts in him. to further the theme of "growth and plants" in the play: the seed is planted by the witches, watered and fertilized by his wife (definitely evil), and HE makes the decision to cultivate and harvest.
He is an honorable man at the beginning of the play, but his decisions (swayed by the women in his life) lead him astray.
I think he is evil in the final analysis. Just because the witches give him a prophesy, does not mean he needs to act. He kills wantonly, sometimes when it doesn't even necessarily benefit him at that moment. While there are many plausible 'excuses' for some of his actions, ultimately I think if you believe in evil, you'd have to say that killing for power is its epitome.
I wouldnt call Macbeth 'evil'. Id prefer calling him disillunsioned. He was a good man, capable of serving his family, the royal famly and the country nobly. He was an efficient soldier and worthy of respect. It was his ambition that became the cause of his downfall. He let his 'vaulting ambition' get the better of his morals, his values and defeat his clear sense of purpose.
The Witches' prophecies coupled with his wife influence were able to spur him on to action and do what he later regretted. But none of this would have possible, had it not been for his ambition, which was an inborn, innate thing. It wasnt his evil nature. It was his greed for power.