The finale of the book of Lamentations captures this ambiguity so nicely:
But you, O LORD, reign forever;
your throne endures to all generations.
Why have you forgotten us completely?
Why have you forsaken us these many days?
Restore us to yourself, O LORD, that we maybe restored;
renew our days as of old --
unless you have utterly rejected us,
and are angry with us beyond measure (Lam 5.19-22).
Here we find some of the central themes of Old Testament religion on full display. First, there is an affirmation of the unique and utter sovereignty of God, who rules over the entire world. YHWH alone is God, and therefore his reign is insuperable.
But to some extent there is an ambiguity about his goodness as a ruler, or barring that, an uncertainty about his rule, even if it was previously affirmed. Why has God forgotten the people of Israel? Why their horrific sufferings? Why have, for example, The hands of compassionate women . . . boiled their own children (4.10)? Why should things have come to this? As he asks earlier, Look, O LORD, and consider! To whom have you done this? Should women eat their offspring, the children they have borne? Should priest and prophet be killed in the sanctuary of the Lord? (2.20). Either God does not reign, his power being compromised in this case, or else he is not good, since he allows such horrific calamities to take place -- more than that, he brings them about himself (e.g., 3.38). There is here a kind of analogy to the Epicurean argument from evil: either God is not good for bringing these things about, or else he is not powerful for failing to prevent them.
The finale even considers a graver, darker possibility: perhaps YHWH has entirely rejected Israel and has nothing more to do with them. Perhaps Israel finds himself in hell now, the utter rejection and abandonment by God. Indeed, the description of the calamities of Jerusalem and Judah is appropriately (even if understatedly) described as hellish! Perhaps life is a hell, and God has abandoned us! Jeremiah would not be the last person to have felt and expressed this line of thought.
Yet in all of this, there is a hope -- no, more than that, a conviction, even if timid -- that God cannot remain like this unto eternity. After a long description of his utter destruction and ruin by the Lord, Jeremiah has the gall to affirm that The steadfast love of the LORD never ceases, his mercies never come to an end (3.22), and that the Lord will not reject forever. Although he causes grief, he will have compassion according to the abundance of his steadfast love; for he does not willingly afflict or grieve anyone (vv. 31-2).
Why should he believe this? Why believe that The LORD is good to those who wait for him (v. 25)?
It seems to me the answer is creation theology. Even though the Mosaic covenant demanded death for disobedience and apostasy, and even though that same prophesied death and destruction has come upon Israel now, yet Jeremiah is confident that things will not remain this way forever. The only way of arriving at this conclusion, to my mind, is to appeal to something beyond the details of the Mosaic covenant; he must appeal to what came before, and which is not nullified by what came after -- and that is the image of the good and loving benevolent creator of Genesis. Jeremiah must have been convinced that the God who created him could not leave him to be destroyed and undone forever.
Even in these final verses of the book there is an implicit trust in the deeper goodness of God, a calm and permanent benevolence beneath the appearance of volatile anger. That is why he pleads, Restore us to yourself, O LORD (5.21). Apart from a trust that YHWH is the sort of God who hears cries of this sort (cf. 3.55-7), even from the very persons he has damned, the request is unintelligible.