Psalm 137 is most likely about the Jews’ exile in Babylon. The Jews in this Psalm are upset that the Babylonians destroyed their capitol city and their temple, and that the Edomites betrayed them to the Babylonians. V 9 states: “Happy shall he be, that taketh and dasheth thy little ones against the stones” (KJV).
This is a controversial verse, especially for Christians who think that it contradicts Christ’s command for people to love their enemies. But I think of something that Charles Haddon Spurgeon says in The Treasury of David:
“Let those find fault with it who have never seen their temple burned, their city ruined, their wives ravished, and after children slain; they might not, perhaps, be quite so velvet mouthed if they had suffered after this fashion. It is one thing to talk of the bitter feeling which moved captive Israelites in Babylon, and quite another thing to be captives ourselves under a savage and remorseless power, which knew not how to show mercy, but delighted in barbarities to the defenceless.”
Excellent point, but are things necessarily that simple? Jesus Christ was mistreated and even killed, and Luke 23:34 (in certain manuscripts) depicts Jesus asking his Father to forgive his persecutors, for they know not what they do.
I can’t judge those who had the sentiment expressed in Psalm 137:9 because, as Spurgeon says, I may have felt the same way that they did were I in a similar situation. Who am I, writing from my computer, to judge people in those kinds of circumstances? At the same time, I would like to have the attitude that Jesus manifested, which looked beyond the pain that the persecutors caused to see their humanity, and to hope even for their spiritual restoration.