The balance of "Good vs. Evil" is dynamic. (The dominance of one pole is alternating by time.) When either gets more robust, the opposite pole gets weaker, and then this process changes - like pendulum swings. Evil will rise as long as some choose to serve as hosts, servants, slaves, workers - as long as someone feeds the corruption. The evil is evil and not wise, not enlightened but selfish, destructive without social abilities, and these disorders, these bad qualities lead the evil to its doom. Perfect balance is assumed to be the key to everything - but even though the universe strives toward such "balance," - ideal balance is a myth. It is not because of some great acceptance of righteousness that a Witch would oppose evil, more that in doing so, the Witch is protecting her authority and, unwittingly, tilting the pendulum for another cycle.