One of the key events in the history of Israel is the Babylonian exile. The Jewish people taken into captivity longed to return to Judah. Psalm 137 presents this longing in a heart-rending retrospect (vv. 1-3) that quickly turns defiant (vv. 4-6) and vengeful (vv. 7-9). The final lines of the psalm depict what one writer called “a horrible kind of happiness.”

“O daughter of Babylon, who are to be destroyed,
Happy the one who repays you as you have served us!
Happy the one who takes and dashes
Your little ones against the rock!”

The psalmist expresses the grief of his situation. He is not expressing the heart of God but reflecting the defiant, vengeful human heart that is part of our lives. The heart of God is found over and over again in the previous psalm: “His mercy endures forever.” God’s mercy is enduring (Psalm 136) while our torment is temporary (Psalm 137).

The Jewish captives in Babylon sat by the rivers in their place of exile, their harps hanging from trees. They were too grief-stricken to sing. Their captors urged them to do so but singing only made them long for home. They forget that their sins led to the destruction of Jerusalem and her temple. The destruction of Jerusalem demonstrates that God’s mercy endures forever, but His justice harmonizes perfectly with that mercy.

Still, there is this matter of Babylon and the atrocities she afflicted on the people of God. The LORD would make that right one day. The captives waited for that day. They pined away for the horrible kind of happiness relayed to us in verse 9. I admit that I have not suffered the fate of these Jewish exiles. This psalm is indeed very emotional and raw. However, there are three very important lessons to learn from it:

1. Judge with the same standard by which you wish to be judged. The standard by which I judge the motives of the psalmist is the standard the LORD shall use to judge my own prayers of defiance and bitterness. Psalm 137.9 is a brutal verse. But I did not live the life of the psalmist. However, God does indeed see me. He knows my own heart as it is reflected back to him during the bitter moments of my life.
2. God does not change. There is not an Old Testament God who evolves into a New Testament God. He is the same yesterday, today, and forever. What has changed is our clarity of the way things are, the way they always have been. We have the entire Word of God, and it is our life. Since God has spoken to us in these last days by His Son, we had better listen. The Lord Jesus taught us to do good to those who hate and persecute us, to bless them and not curse them.
3. Find the right kind of happiness in the Gospel. The cross of Christ changes everything. It removes a vindictive, vitriolic spirit. If we believe on the death of Christ for our sins and the resurrection of Christ for our righteousness, then the horrible kind of happiness in Psalm 137.9 will give way to the right kind of happiness among the blessed who are merciful. This is true because the merciful obtain mercy themselves. They understand their own need of mercy and see themselves in their Babylonian captors. They understand that only God is just and only God is able to put the world right.