Western Christianity, with its odd mixture of pagan and secular moral values, struggles to understand the moral content of this psalm. This psalm is a good test of whether one can grasp the Ancient Hebrew outlook that is at the core of Christ’s teachings. This psalm is very much like a brief skit or play.
The Judean exiles would have gathered along the riverbanks as part of their normal grieving rituals. It would include baptism, a symbolic washing away of sins. They were there because of God’s wrath and they understood all too clearly that they had sinned against Jehovah. It’s not that any particular patch of dirt on this planet is so much better than another, but that God had removed their status as a sovereign nation. They were now dependent on the tolerance of their hosts. They could grow fine crops and keep large herds, do business and even engage in banking, but it wasn’t their homeland where God had allowed them to build the Temple to bear His name proudly.
So as a symbol of their sorrows, they hung their musical instruments on the willow trees growing there along the river’s edge. It’s hard to be certain of the exact symbolism, but from where we stand today, it’s obvious they had no intention of using those instruments to celebrate anything. Mourning and lament was properly a capella in their culture.
When the local rulers came to visit, seeing the instruments in the trees, they would have naturally asked for some of the worship songs for which Judeans were famous. We cannot ignore the likelihood that those local masters knew it would have been sacrilege; Babylonians had cataloged the world’s religions and knew plenty about the worship of Jehovah. So there was a bit of mocking here, along with genuine curiosity to hear an authentic rendition of such music, since such music was always passed on by tradition, never in any written notation.
The depth of lament is moving even for us today. There is only one purpose for such music, and without the Temple, it was simply impossible to perform. It’s not a mere matter of nostalgia for the homeland, but the symbol of Zion as the Holy City of God. Thus, this was a sense of sorrow and loss writ across the land and sky for the Hebrews. They would rather cease knowing who they were and die where they stood, than to make a game out of working through their repentance at this point. They knew God was merciful; they knew the captivity had a time limit.
They also knew that God promised He would not treat them the same as He did the rest of the world. It was already well established in Hebrew theology that the Devil was a figure for the demonic adversary that served as God’s punishing hand. There were some people in this world who were fully the property of Satan; if one is going to hate Satan, one must hate his children. If the Nation of Israel was going to be a political entity on this earth, then there had to be political outcomes to their moral battles. Real politics meant real bloodshed. Israel was the literal reality expressing a very deeply mystical truth.
Israel had a mission to give life to the revelation of God. For reasons Israel well understood, He had unleashed the Adversary on Israel until recompense was made, and it was time to restore His witness on the earth. His witness included His wrath against sin. Wrath on His witnesses — His own adopted family — was one thing. Wrath on those who rejected His witness was another thing.
So the psalmist makes mention of their cousins, the Edomites, children of Esau. He understates the case; Edom did more than just celebrate the destruction of Jerusalem. They actively supported the Babylonian siege, helped plunder Judah, and generally did everything possible to offend Jehovah personally by attacking His people. Even when Babylon later turned on Edom and plundered them, as well, the Edomites were still crowing about the removal of Judah. They were a living manifestation of deep and ceaseless violence against God’s moral character written into Creation itself, and they were very proud of it.
The psalmist also prays a blessing on whomever God was preparing to raise up against Babylon. Judeans had no doubt an enemy of Babylon was out there, that God was at work on that future day of conquest. His prophets made clear that His favor on Babylon was rather like a man for any good tool that would same day wear out. He had never planned on making them family. Given the Babylonian troops dashed Judean children against stones and sliced open pregnant women, it was mere justice that something similar would happen to them when the day of recompense came.