Psalm 137. That's in the Bible!? -by pastor steve york

​Psalm 137 is a Psalm written in the context of the Babylonian captivity; the Jewish people had been attacked and taken to Babylon where they were enslaved by their enemies. 
When we read Psalm 137 today, especially the last verse, we wonder, “How can this be in the Bible?” 

Happy is the one who takes your babies and smashes them against the rocks! -Psalm 137:9

Some important things to keep in mind: 

1. Understand the context of the Babylonian captivity and the promises of God for His people, the Jews. Psalm 137 is a cry for justice and salvation from their enemies, the ones who had enslaved them, killed their own babies, and destroyed and burned their city, Jerusalem.
2. The Psalms often express intense emotion, and Psalm 137 is no exception! God can handle intense emotion, and wants us to express our emotions to Him in prayer.
3. Today, we as well want justice, but we need to be careful to apply this in the context of all of Scripture. We are told in the New Testament:“do not repay evil with evil” (1 Peter 3:9)  and to not seek revenge, for God will bring about justice (Romans 12:19).
4. Lastly, it is important to recognize that this Psalm is not a prayer for personal revenge, but a prayer for God to fulfill His promises of saving His people from their enemies. 

Check out this short video from GotQuestions.org if you want to dig into this a bit more.