Basically, Jeremiah is preaching to the Jews as they are about to be conquered totally by the Babylonians. It occurred in waves, with the fall of Jerusalem coming in 586 B.C. Although Judah saw the 10 northern tribes of Israel conquered for idolatry in 722 B.C. by the Assyrians, the two southern tribes (Judah and Benjamin) did not take heed and repent of their wickedness. They suffered the same fate at the hands of Babylon.
As I have been reading through this book, a similar phrase has occurred repeatedly, and it brings to mind the book of Judges. Look at the following passages from Jeremiah:
3:17 - At that time they will call Jerusalem ‘The Throne of the LORD,’ and all the nations will be gathered to it, to Jerusalem, for the name of the LORD; nor will they walk anymore after the stubbornness of their evil heart.
7:24 - Yet they did not obey or incline their ear, but walked in their own counsels and in the stubbornness of their evil heart, and went backward and not forward.
16:12 - You too have done evil, even more than your forefathers; for behold, you are each one walking according to the stubbornness of his own evil heart, without listening to Me.
18:12 - "They will say, ‘It’s hopeless! For we are going to follow our own plans, and each of us will act according to the stubbornness of his evil heart.’"
Judges 17:6 and 21:25 both state that there was no King in Israel during the time of the Judges, and every man did that which was right in his own eyes. That sounds much like the passages from Jeremiah. The people were about to go back into captivity, and they would not listen to the word of God. They wanted to do what their own wisdom and counsel told them. They trusted in the physical temple, the priesthood, Old Covenant rituals, etc. However, they did not listen to or obey God's word (16:12 above).
Sadly, it sounds quite a bit like churches and professing Christians in our own day. We claim "God told us..." about so many things, but these things are often contrary to Scripture. Instead of being instructed by God, we are actually walking as the Jews did in Judges and Jeremiah. God will never violate His written word!
Our minds are not trustworthy when it comes to wisdom and knowledge unless they are informed and taught by the word of God. God has not left it up to us to "dream a dream, and then go for it." The only way that we will be mature believers is to be taught by, reproved by, corrected by, and instructed by Scripture (2 Tim. 3:16-17).
Listen to just a few texts from Proverbs.
Prov. 28:26 - Whoever trusts in his own mind is a fool, but he who walks in wisdom will be delivered.
Prov. 12:15 - The way of a fool is right in his own eyes, but a wise man listens to advice.
Prov. 26:12 - Do you see a man who is wise in his own eyes? There is more hope for a fool than for him.
How much time do you spend renewing your mind according to the truth of God's word (Rom 12:1-2) instead of trusting your own thoughts, reasoning, intellect, understanding, experiences, etc?
May God give us the grace and resolve to meditate in his word day and night (Psalm 1).