The battle between good and evil begins in the realm of shadow, where the precise locations of good and evil are not clearly recognizable.
But at the moment that certainty exists, at the moment that there is a face-to-face confrontation and a person cries out upon recognizing the evil, “You are evil, wicked, disgusting, loathsome, and abhorrent!” the battle has been decided, the lamp has been lit, and the shadows fade.
–Rabbi Adin Steinsaltz