Jeremiah 4: false assurance that Judah is safe

 
In Jeremiah 4, the Lord says:

 “If you want to come back, O Israel,
    you must really come back to me.
You must get rid of your stinking sin paraphernalia
    and not wander away from me anymore.

...

Here’s another Message from God
    to the people of Judah and Jerusalem:
“Plow your unplowed fields,
    but then don’t plant weeds in the soil!
Yes, circumcise your lives for God’s sake.
    Plow your unplowed hearts,
    all you people of Judah and Jerusalem.
Prevent fire—the fire of my anger—
    for once it starts it can’t be put out.
Your wicked ways
    are fuel for the fire.

Jeremiah calls Israel and Judah to come back to the Lord otherwise the fire of the Lord's anger will burn their wicked ways. The invasion from the north is coming:

6 Raise a flag toward Zion!
Take refuge, do not stand still,
For I am bringing evil from the north,
And great destruction.

Jeremiah questions the Lord:

10 Then I said, “Alas, Master God!
    You’ve fed lies to this people, this Jerusalem.
You assured them, ‘All is well, don’t worry,’
    at the very moment when the sword was at their throats.”

The Lord is warning Jerusalem about the coming destruction through the prophet Jeremiah, however Jerusalem is deceived, assured that everything is well. Interestingly the prophet blames the Lord for it. Yet:

11 At that time it will be said to this people and to Jerusalem, “A scorching wind from the bare heights in the wilderness, in the direction of the daughter of My people—not to winnow and not to cleanse, 12 a wind too [d]strong for [e]this—will come [f]at My command; now I will also pronounce judgments against them.”

I understood that this scorching wind refers to the evil from the north in verse 6, i.e., Babylon.
The Lord is showing the coming destruction to Judah but still, there is hope:

14 Wash your heart from evil, Jerusalem,
So that you may be saved.
How long will your wicked thoughts
Lodge within you?

...

18 Your ways and your deeds
Have [h]brought these things upon you.
This is your evil. How bitter!
How it has touched your heart!”

The prophet laments the coming destruction given that Judah has no understanding:

21 How long must I see the flag
And hear the sound of the trumpet?
22 “For My people are foolish,
They do not know Me;
They are foolish children
And have no understanding.
They are skillful at doing evil,
But they do not know how to do good.”

23 I looked at the earth, and behold, it was a [m]formless and desolate emptiness;
And to the heavens, and they had no light.
24 I looked on the mountains, and behold, they were quaking,
And all the hills jolted back and forth.
25 I looked, and behold, there was no human,
And all the birds of the sky had fled.
26 I looked, and behold, [n]the fruitful land was a wilderness,
And all its cities were pulled down
Before the Lord, before His fierce anger.

Judah sought alliances with Egypt and Assyria (her lovers) in vain:

30 And you, desolate one, what will you do?
Although you dress in scarlet,
Although you adorn yourself with jewelry of gold,
Although you enlarge your eyes with makeup,
In vain you make yourself beautiful.
Your [p]lovers despise you;
They seek your life.  

31 For I heard a voice cry as of a woman in labor,
The anguish as of one giving birth to her first child.
The voice of the daughter of Zion gasping for breath,
Stretching out her [q]hands, saying,
“Ah, woe to me, for [r]I faint before murderers.”