Chapter 4 is not a pleasant chapter. Judah refuses to repent, and the Lord promises destruction will come from the north and ruin the land. You wonder by God would choose such a people:
22 “My people are fools;
they do not know me.
They are senseless children;
they have no understanding.
They are skilled in doing evil;
they know not how to do good.”
I think the answer is that they are a metaphor for the natural tendency of the sinful human heart. And that God must judge sin. Only his mercy keeps him from reigning down utter destruction, as he reveals:
27 This is what the Lord says:
“The whole land will be ruined,
though I will not destroy it completely.
There is always this declaration of judgment, but . . . We know judgment will never be total because of God’s unilateral covenant promise to Abram in Genesis 15. Especially the ceremony he performs walking through the line of dead animals, which says in ancient Near Eastern custom, may I be like these animals if this covenant is not fulfilled. The rebellion of man is no contest for the living God!
Chapter 5 continues the same theme. It’s not only that Judah does evil, but the rebellious attitude in which they do it. For instance:
3 Lord, do not your eyes look for truth?
You struck them, but they felt no pain;
you crushed them, but they refused correction.
They made their faces harder than stone
and refused to repent.
The sex metaphors continue as well:
Your children have forsaken me
and sworn by gods that are not gods.
I supplied all their needs,
yet they committed adultery
and thronged to the houses of prostitutes.
8 They are well-fed, lusty stallions,
each neighing for another man’s wife.
And in their pride they delude themselves that they will not be judged or punished for their sin:
12 They have lied about the Lord;
they said, “He will do nothing!
No harm will come to us;
we will never see sword or famine.
They do not even acknowledge that the Lord is the Creator, and that they are dependent on him for everything. Their deeds reflect an utter lack of gratitude or reverence for the Lord. Not every sinner is as evil as they can be, but “good” people without the Lord refuse to acknowledge they he is God and that they are not.