Please help me find some valid arguments for my thesis on Macbeth.
I'm saying that the witches are angels who arrived on earth to judge the potential evil inside Macbeth, and finally punish him. Here's some of my planning.
I see a few major problems with this thesis, as interesting as it is. The first most major barrier to arguing your case is the fact that the witches are intentionally associated with evil forces and activities from the very beginning of the play. This makes it very hard for them to be considered as "angels." Note the way in which Act I scene 1 indicates that they have familiars, a special, mystical relationship with animals that only witches possessed. In addition, note their purpose as expressed in the chant they utter at the end of this opening scene:
Fair is foul and foul is fair:
Hover through the fog and filthy air.
This in a sense can be used as a motto of this brilliant play, as it points towards the theme of appearances vs. reality. The witches' purpose and job is to turn what is good into what is bad, and to deliberately disrupt goodness and morality. The way that this purpose is associated with the "filthy air" and the darkness with which the witches are associated makes it absolutely clear that these figures cannot be "angelic" in any sense of the word.
Secondly, I think you need to think about what the witches do with Macbeth. You state that you think the witches come to judge the potential evil in Macbeth and then judge him. Why then do they seem to deliberately taunt him with half-truths and unclear prophecies? Note how Macbeth responds in Act I scene 3 to the prophecies of the witches:
The witches deliberately deal in half-truths, presenting characters with contradictory sentences that are meant to confuse, obfuscate and darken. Again, this is hardly the kind of thing that we would expect angels to do.
So, while I think you are arguing something very interesting, I don't personally believe there is evidence from the text to support your main ideas. I hope this helps clarify your thinking.