“You have multiplied your slain in this city, and you have filled its streets with the slain. Therefore thus says the Lord Yahweh, ‘Your slain whom you have laid in its midst, they are the flesh, and this city is the cauldron, but you will be brought forth out of the midst of it. You have feared the sword and I will bring the sword on you, says the Lord Yahweh'.”
The reason for God's unrelenting judgment was made clear. Murder had been, and still was, rife in the city, even judicial murder. Rivals were removed, and good men who protested were executed under false pretences. Life had been, and was, violent, for the commands of Yahweh were being ignored (compare Jeremiah 22:3). Their sins were unrelenting. They were still refusing to learn their lesson.
There is then a play on their own illustration. This can be taken in two ways. 1). Rather than their being the flesh in the cauldron, it was the dead at their hands who were the flesh in the cauldron, for it had proved a cauldron of death. Rather than the cauldron acting as a protection from outsiders it had caused the death of the good flesh brought about by those within the cauldron. 2). That it is the slain alone who could rejoice in the protection of the cauldron, for they have been rescued by death. For those still alive it would provide no protection.
If the leaders were seeing themselves as the good flesh, as they probably were (compare Ezekiel 11:15), then Ezekiel may be pointing out that in truth they were the ones who had actually slain the good flesh, those who had been faithful to Yahweh, by purges and persecution. Thus He was declaring that He would not protect these men of violence, for they would be brought out of Jerusalem and suffer the fate that they feared, and that they had brought on others, the avenger's sword, (this supports the first interpretation of Ezekiel 11:3). And it would be brought on them by the Lord Yahweh Himself Who had deserted the city (Jeremiah 12:7).
Note the stress on ‘the Lord Yahweh'. Here was the root of the problem. They were ignoring, no, even rebelling against, the One Who was truly Lord over them. They were not just ignoring and rebelling against Nebuchadnezzar, and breaking a treaty with him, they were ignoring and rebelling against their own covenant God and His treaty.