The Lord has done what he purposed,
has carried out his threat;
as he ordained long ago,
he has demolished without pity;
he has made the enemy rejoice over you,
and exalted the might of your foes. (Lamentations 2:17 RSV)
In other words, God is faithful. Suddenly Jeremiah realizes that this is consistent with the character of God. If he says he is going to do something, he will do it. Nothing can make him change. If you look back over the history of Israel you discover that in the book of Deuteronomy, God had said to Moses, “Moses, if my people walk in obedience to me and love me and follow me, I will pour unlimited blessing upon them. I will open the windows of heaven and just simply bless them until they can’t stand it. But if they turn, if they go aside, I will plead with them and send prophets to them and work with them and have patience with them.” (And the record is that for four hundred years, God put up with the intransigence of Israel.) But God also promised that if Israel followed after other gods, he would raise up a nation to come in and devastate the land. That is exactly what God said and that is exactly what he did.