Take a closer look at the forces that you normally consider to be evil and you may well find that they are not quite as bad as you thought. There are many examples to show us that what is bad for some is not necessarily bad for others.
Some animals for instance have an extraordinary resistance to fire; others to cold; others to certain kinds of poison, and yet others to a lack of food. There are even some that are not killed when their body is cut in two! Humans have forged their own ideas about evil that are valid for them, but they are not universally valid.
They cannot really know what evil is as long as they judge it from the viewpoint of their own weaknesses and limitations. As they begin to approach perfection their ideas will change, just like Initiates who, looking beyond the fearful aspect of evil that terrifies the weak, are able to discern in it a beneficial force or even a friend.