Witches' role in Macbeth

I do not like the witches in Macbeth. I think the witches are source of evil in Macbeth. If it wasn't those witches, how could Macbeth think of killing the king. He would be a loyal servent to king Duncan and his country. Without the predictions, there will not have anything like the mess Macbeth has made, the land of Scotland would be peaceful. It is those witches' predictions which make his mind insane. The witches are responsible for king Duncan's death. They are the ones that make Macbeth to do as their will, inorder to let Macbeth believe to them, they make the first two predictions true so that, Macbeth would be eagerly to become the king. These witches are the true murderers of Duncan. That is why I think the witches are source of evil in Macbeth.