7 Therefore this is what the Lord Almighty says:
“See, I will refine and test them, for what else can I do because of the sin of my people?
8 Their tongue is a deadly arrow; it speaks deceitfully. With their mouths they all speak cordially
to their neighbors, but in their hearts they set traps for them.
9 Should I not punish them for this?” declares the Lord.
“Should I not avenge myself on such a nation as this?”
The Lord makes it clear through His prophet Jeremiah, it is the condition of the heart in which He is interested and when He finds it full of deceit He is not happy and judgment is not far behind.
11 “I will make Jerusalem a heap of ruins, a haunt of jackals; and I will lay waste the towns of Judah so no one can live there.”
When He finds hearts full of deceit, He also usually find stubbornness in the hearts leading to great evil as evidenced in a few verses following those above
13 The Lord said, “It is because they have forsaken my law, which I set before them; they have not obeyed me or followed my law. 14 Instead, they have followed the stubbornness of their hearts; they have followed the Baals, as their ancestors taught them.”
It was no small matter that they worshipped Baal as historical sources tell us they often sacrificed their children to this false god.
The archaeological record seems to bear out accusations in Roman sources that the Carthaginians burned their children as human sacrifices to him. Wikipedia
Jeremiah concludes this chapter with the Lords condemnation of Israel due to the condition of their hearts, that their hearts are uncircumcised like those of other nations.
25 “The days are coming,” declares the Lord, “when I will punish all who are circumcised only in the flesh— 26 Egypt, Judah, Edom, Ammon, Moab and all who live in the wilderness in distant places. For all these nations are really uncircumcised, and even the whole house of Israel is uncircumcised in heart.”
What an incredible indictment of the people of Judah/Jerusalem to be grouped with such unbelieving nations because they were only circumcised in the flesh and not in the heart. Paul addressed fleshly circumcision when he said
For in Christ Jesus neither circumcision nor uncircumcision has any value. The only thing that counts is faith expressing itself through love. Galatians 5:6
In Him you were also circumcised with a circumcision not performed by human hands. Your whole self ruled by the flesh was put off when you were circumcised by Christ, having been buried with Him in baptism, in which you were also raised with Him through your faith in the working of God, who raised Him from the dead. Colossians 2:11-12
Of course the only way faith can express itself through love is through a circumcised heart! We would do well to check the condition of our hearts.