If we “tone down” the cry against injustice as something “primitive,” we cannot appreciate the cross—because there we see that the punishment for such cruelty is exactly what the Psalmist has called for. We see God’s “little one” being dashed to pieces. Yes, the punishment that human injustice and evil deserves is just as bad as the imprecation stated! But what the Psalmist could not see is that when God’s Messiah came the first time, He came to bear the judgment on human evil, not mete it out. And the Psalmist could not see that he deserves to be condemned as well for his own life-record. At the Psalmist’s “stage in Redemptive-History,” he was stating truth as far as he could see it. But we now have been both humbled by the cross (so we cannot cry for vengeance in the same way) and we have been given enormous hope by the cross. We see that God will do justice in the earth. He is so passionately against it that He experienced it Himself so that He could some day end all evil without ending us. This keeps me from having to put my self in his place and become sucked up into the endless cycle of vengeance and retaliation.
–Tim Keller, Preaching the Gospel in a Post-Modern World, 54