Jeremiah 3:11 The LORD said to me, "Faithless Israel is more righteous than unfaithful Judah.

This previous statement is made regarding their pretense.  Faithless Israel is devoid of faith, they have no faith.  Unfaithful Judah claims to be faithful and yet is unfaithful.  This makes Judah worse than Israel yet Israel doesn't even claim to acknowledge God. 

Faithless Israel "has gone up on every high hill and under every spreading tree and has committed adultery there." Most always the phrase "under every spreading tree"  is related to sexual sins.

Jeremiah relates that the entire house of Israel (all 12 tribes) have been unfaithful as a woman is unfaithful to her husband.  Again, the marriage analogy of God's relationship with His people.  God urges the people to return to Him. The scattered tribes will return in the millennium. Jews are being brought back into the land today. (see Ezekiel 37) He says He will bring them to Zion which is exactly what the Messianic Jews are doing today. Couldn't help but think of Moshe in Israel concerning the shepherds who lead the people with knowledge and understanding.

2 Timothy 2:13
if we are faithless, he will remain faithful, for he cannot disown himself.

We have an amazingly gracious God. He remains faithful to us - even when we are not faithful to Him! God reminds us through Jeremiah as He did with Isaiah that our relationship with Him is as a spiritual marriage. 

Jeremiah 3:13 Only acknowledge your guilt -

This is a very important verse that reminds us of the need to acknowledge our sins and repent, then the blessings will come.

Jeremiah 4:3
This is what the LORD says to the men of Judah and to Jerusalem: "Break up your unplowed ground and do not sow among thorns.

Unplowed ground is as a hardened heart…not open to hearing and applying the Word of God. We are told to break up this unplowed ground. How can we do that? Does this mean that we are to soften our hearts and rid ourselves of the briars and thorns of soft teaching and man-made traditions? 

He also tells us not to sow among thorns. Later in this same chapter we find this verse.

Jeremiah 4:22b
They are skilled in doing evil; they know not how to do good."

If we sow among thorns, we reap destruction.  If a person does not know how to do good, could it be that they have not been taught God's ways?   We take great pains to use herbicides to kill weeds in our lawns but we tend to spend little energy to kill the spiritual weeds in our faith.

Galatians 6:8a
The one who sows to please his sinful nature, from that nature will reap destruction;

Skill in doing evil comes from practicing that which is evil. It is called "usage familiarity".

Best advice: Break up our “unplowed ground” and allow God’s Word to take root and grow.

In Jeremiah 4:10 he accuses God of deception - a serious accusation!

Later in Jeremiah 4 are descriptions of a vision that Jeremiah was given concerning what is to come if the people do not repent and return to the Lord.

Jeremiah 5:1
“Go up and down the streets of Jerusalem, look around and consider, search through her squares. If you can find but one person who deals honestly and seeks the truth, I will forgive this city.

This one person who deals honestly and seeks the truth would be an example of a modern-day prophet. Does this mean that God will forgive a nation if a remnant repents?  Is this a confirming verse for the Power of ONE person?

Jeremiah 5:2
Although they say, ‘As surely as the Lord lives,’ still they are swearing falsely. ”

People may go through the motions, giving "lip service" to repentance but don't mean it.  How about many politicians who swear on the Bible that they will uphold the constitution of the United States and then immediately violate the oath they just took?

Jeremiah 5:3
O 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.  

We, as a nation and a church, have been given warnings about repentance, and yet we have not turned.

So in the next few verses Jeremiah thinks that maybe the people just don't know how to repent, they don't know the way of the Lord.  He thinks he will go to the leaders, surely they will know.  But, of course, they don't.  And so God lets Jeremiah know the fate of those people.

We just keep going back to the verse in chapter 5.
If you can find but one person who deals honestly and seeks the truth, I will forgive this city.
One person CAN make a difference!  Never forget the power of ONE.