John Calvin's Bible Commentary
Jeremiah 19:9
Here the Prophet goes farther — that so atrocious would be the calamity, that even fathers and mothers would not abstain from their children, but would devour their flesh. This was indeed monstrous. It has sometimes happened that husbands, in a state of extreme despondency, have killed their wives and children, (anxious to exempt them from the lust of enemies,) or have kindled a fire in the midst of the forum, to cast their children and wives on the pile, and afterwards to die themselves; but it was more barbarous and brutal for a father to eat the flesh of his son. The Prophet then describes an unusual vengeance of God, which could not be classed among the calamities which usually happen to mankind.
We know that this was also done in the last siege of that city; for Josephus shews at large that mothers in a brutal manner slew their children, and that they so lay in wait for one another that they snatched at anything to eat. This was also an evidence of God’s dreadful vengeance.
But it was no wonder that God visited in such an awful manner the sins of those who had in such various ways, and for so long a time, provoked him; for if we compare the Jews with other nations, we shall find that their impiety, and ingratitude, and perverseness, exceeded the crimes of all nations. Then justly did God inflict such a punishment, which even at this day cannot be referred to without horror. The whole indeed is to be ascribed to his judgment; for it was he who fed (218) the fathers with the flesh of their children; for as they had sacrificed their sons and their daughters to demons, as before stated, so it was necessary that the vengeance of God should be openly pointed out as by the finger. This was done when God imprinted marks on the bodies of children, which even the blind could not but perceive.
He adds, In the tribulation, (219) and straightness with which their enemies shall straiten them. We have said that those who had been long besieged, and were not able to resist, have been often reduced to the necessity to freeing their wives, or their children, or themselves, from dishonor; but to protract life in the manner here mentioned was altogether brutal. It follows —