1. “Imprecatory Psalms,” is a misnomer. They are Psalms of Justice. They are what the world needs most. We have extolled the love of God to the exclusion of His justice. The justice of God must not be sacrificed on the altar of His mercy.
2. If you start deleting these so-called Imprecatory psalms, what are you going to do with the words of the "gentle" Savior in Luke 3:7 and Matthew 23:33 (in fact in this whole chapter)?
3. Something else people tend to forget, or overlook is that what is written in Psalm 109 actually came to pass. It is a prophetic description of Judas and what happened to him. It is what happens to any man who hardens himself against the Spirit of God. What do you suppose God is going to do with men like Judas? What can God do with wicked men? He lets sin take its course. "He (Judas) clothed himself with cursing." "Let it be unto him as the raiment.” Judas spurned a wedding garment, so he was clothed in God's curse against his sin. "Sin when it is finished brings forth death."
4. The poet Henry Van Dyke wrote against the Imprecatory Psalms, as did C.S. Lewis. Ironically, during World War I, when the Germans were going through Belgium, Henry Van Dyke used language against the Germans as strong as you can find in any of the Imprecatory Psalms. Yet he, like C.S. Lewis, said the spirit of these Psalms was "unchristian."
5. If we believe the Scriptures to be God's Word, then we believe that God has composed these Psalms. If God has composed a Psalm, a Christian is safe enough in singing it and praying it. If God does the thing that is predicted, a Christian should have no compunction singing about what God does.
6. Psalm 137:8 is simply in accord with what Christ Himself said: "As a man sows so shall he also reap."
If you take out the Imprecatory Psalms, you must consistently take out every passage that speaks of the justice of God in meting out punishment to sinners. You will have to take out every description of the judgment and what will you have left to preach ?