Almost in unison came the answer: "The anger of God."
You couldn't miss it. The poet uses three Hebrew nouns 7 times along with two verbal expressions for anger. Then you have the list of things God did in His anger—and there was no quibbling about it: God did them, not the Babylonians. He "laid waste his booth," " laid in ruins his meetingplace," "spurned king and priest," "made Zion forget Sabbath," "scorned his altar," and "disowned his sanctuary." He destroyed the very worship he had set up for his people and the people seemed to have no trouble recognizing that God had every right to do it. They broke the Covenant. It was all their fault.
Today we all want to focus on the God of love. I know it when I hear things like, "God wants me to be happy. He would never be angry about such a little thing. He would never _______________."
First of all, what God wants is for us to be holy so we can spend an Eternity with him. We cannot if we are anything less than pure because we couldn't—wouldn't—give up the pleasures of even the smallest of sins, and that means that sometime we won't be very "happy.". "Sin separates you from God." If, after all the blessings I have received from Him and after the huge sacrifice He made for me, I am so unspiritual that I cannot make a relatively insignificant sacrifice for Him in order to make myself acceptable, I deserve His anger and whatever punishment goes along with it. Yes, He will too ____________, and even these stubborn, selfish, prideful, ungrateful, unmerciful, and unfaithful people of His eventually figured it out.
For us to picture God as a one-dimensional Being who only forgives and loves is nothing short of arrogant. God as our Creator has every right to be angry with the created ones who break His laws. When unbelievers blast God for that anger—"How could a just God allow these things to happen?"--don't think you have to apologize for Him. He doesn't need us to explain it away in order to make Him more palatable to a shallow, ungodly, and disobedient world now any more than He did then.
The Lord has swallowed up without mercy all the habitations of Jacob; in his wrath he has broken down the strongholds of the daughter of Judah; he has brought down to the ground in dishonor the kingdom and its rulers. He has cut down in fierce anger all the might of Israel; he has withdrawn from them his right hand in the face of the enemy; he has burned like a flaming fire in Jacob, consuming all around. He has bent his bow like an enemy, with his right hand set like a foe; and he has killed all who were delightful in our eyes in the tent of the daughter of Zion; he has poured out his fury like fire. The Lord has become like an enemy; he has swallowed up Israel; he has swallowed up all its palaces; he has laid in ruins its strongholds, and he has multiplied in the daughter of Judah mourning and lamentation. (Lam 2:2-5)