An intriguing example in ancient Hebrew literature of the devil we do not know is found in the book of Job. This biblical and world classic opens with God boasting about his servant Job, a pious man unsurpassed in his character and integrity. Satan, the accuser, overhears God’s boast upon this his model creature and challenges God’s proud description of Job. He says that if you take away all that you have given him—children, wealth, reputation—he will curse you and die. Satan is a behaviorist. As you may recall, God allows Satan to take away everything including Job’s health but no more and Job descends into a dark night of the soul. His friends come to comfort him in his unspeakable grief, sitting silently with him on the ash heap for a week. When they finally speak to him, they become, like Satan, his accusers, declaring that the only explanation for his affliction is that he has sinned against God. Job defends himself round after round, saying that he has done nothing to deserve such suffering. The mysterious part of these arguments between Job and his friends-turned-accusers is that none of them even hint at the existence of a malevolent creature like Satan. We the readers know that he is behind Job’s losses and laments, but for Job and his accusers, he is the devil you don’t know. And he is never mentioned again after the opening two chapters.
– Daniel Russ and Gregor Thuswaldner, “The Devil We Know and the Devils We Don’t Know,” The Hermeneutics of Hell: Visions and Representations of the Devil in World Literature (2017)