How is Macbeth a statement of evil and how do others contribute to this?

Although Macbeth gradually embraces evil, viewing him only in terms of his criminal behavior is not a precise examination of his character. When we take a look at his soliloquies, which often reveal his fears and doubts, we can realize Macbeth is a complex character who has a conscience. Even when he tries to come across as brutal and evil, his conscience keeps haunting him. In his famous soliloquy when he proclaims life is futile,...

Although Macbeth gradually embraces evil, viewing him only in terms of his criminal behavior is not a precise examination of his character. When we take a look at his soliloquies, which often reveal his fears and doubts, we can realize Macbeth is a complex character who has a conscience. Even when he tries to come across as brutal and evil, his conscience keeps haunting him. In his famous soliloquy when he proclaims life is futile, Macbeth realizes our lives mean nothing in particular. We are mere shadows on the planet, and the power we gain is temporal. If Macbeth were wholly evil, he would be preoccupied with causing more harm and would not think about the futility of life and other philosophical issues. 

Although Macbeth alone is to blame for initiating his own downfall, his wife and the witches have an impact on him. Lady Macbeth's persuasive speech motivates Macbeth to go after his "black and deep desires." The witches' prophecy is another factor that influences Macbeth. He becomes obsessed with the prophecy and decides to take matters into his own hands.