Strictly speaking, there is no such ‘thing’ as evil. For as darkness is the absence of something – light – so evil is the absence of something – love.
This is not to say that evil is an illusion: the withholding of love has real and terrible impact on those from whom it is with-held, and upon those who choose to withhold. It does mean, however, that we cannot allow ourselves the easy luxury of calling our enemies evil. Firstly, because they are something, having substance – substance, moreover, created in the image of God – and evil has no substance. And secondly, because by passing judgement in calling them evil, it is ‘our’ freely-chosen inaction of withholding love that allows evil to eclipse good.
Instead, we are called to love our enemies, and in so doing to participate in Love, which is the greatest thing of all.