We cannot think of evil in impersonal terms. Temptation is a voice suggesting another course of action, as when Jesus was tempted. Enslavement needs humans to do the enslaving. You can only be deprived of dignity by one or more persons. Unjust accusation needs an accusing voice.
Oppression needs an oppressor, and being abused an abuser.
It is only a personal being who can deny love and compassion. This is why the city of Babylon was addressed in very personal terms as Lucifer. In our own day Communist Russia was personalized by Stalin, the Nazi regime was personalized in Hitler, and the media personalized Iraq's militarism in Saddam Hussein. Evidently humans find it easy to assign personality to powers that they consider unjust or oppressive. That is why the names we give to the source of evil are bestial, dragonish, snake-like.