From David Clines’ Job 1-20:
12 So naturally does Yahweh’s agreement to the proposal follow that we are compelled to pause in order to ponder its implications. Are we to condemn the figure of Yahweh here for his alacrity and cold-bloodedness (Duhm) in assenting to such a scheme? And do we find in the prohibition of harm to Job’s person the one lingering sign of Yahweh’s affection for his servant? Or is it that God himself does not need to be convinced of Job’s disinterested piety, but is prepared to allow the Satan to satisfy himself of its reality (Rowley), or, to put it more positively, accepts the challenge in order to vindicate his servant against the insinuations of the Satan (Peake)? Or are we to say, most improbably of all, that God assents to the trial of Job’s piety in order to refine or deepen Job’s faith?
All these suggestions attribute to the narrative a subtlety it does not bear, at least in its essential story-line. God can agree to the proposal to “smite” all that is Job’s only because he too, like everyone else, does not know what the outcome will be. The Yahweh of this tale is not the absolutely omniscient God of later systematic or speculative theology. He is wise beyond human comprehension, for his “eyes” and “ears,” like the spies of the Persian kings, are everywhere abroad, and report to him on days of assembly (cf. v 6). But not even Yahweh knows what has not yet happened; his knowledge does not encompass all possible hypothetical situations. He has confidence in Job, but not a confidence that would enable him to use Job as an object lesson to refute the Satan’s aspersions. He too has taken it for granted that he will bless the pious man; but that benign reciprocity has obscured the true relation of piety and prosperity. The Satan has the right to ask the question, and Yahweh is in the right in having the problem probed.
The alternative to such a reading of the story is worse. Affirm that Yahweh is infinitely omniscient, and you assert that Job’s suffering serves only to prove God right in the eyes of one of his subordinates. Affirm that Yahweh knows that Job will not waver, and you cannot explain why Yahweh takes the slightest notice of the Satan’s questions or why he does not dismiss them out of hand from superior knowledge.