Another gem of a passage from Bauckham’s The Bible in Politics, offering perhaps the most satisfactory discussion of the issue of imprecatory psalms and forgiving enemies that I have yet read:

“The oppressed Christian who discovers Jesus’ solidarity with him must take account of one respect in which Jesus in his suffering prayed differently from the way the psalmists prayed.  Jesus prayed for his enemies’ forgiveness (Luke 23:34), thus practising his own teaching (Matt. 5:44).  The psalmists never did this: their attitude to their enemies is consistently unforgiving.  They pray for God’s judgement on their enemies (Ps. 10:2b, 15), sometimes in the form of solemn and extensive curses (Ps. 69:22-8; 109:6-20).  But such prayers are not unknown in the New Testament (Rev. 6:10).  They need to be accorded a kind of provisional validity, which does not excuse any Christian from the duty of forgiving enemies, but does help us to understand what is really involved in forgiveness.  Jesus’ demand for forgiveness of enemies does not, we might say, simply revoke these prayers, but takes a step further beyond them.  We have to appreciate what is valid about them before we can rightly take, as followers of Jesus must take, that further step.  

First, these prayers spring directly from the psalmists’ demand for justice.  Like the widow in Jesus’ parable, whose demand was for the judge to vindicate her against her adversary (Luke 18:3), the psalmists’ primary concern is positive—justice for the oppressed—but they cannot envisage this without its negative corollary—justice against the oppressor.  Nor, in concrete situations of political injustice, is it often easy for us to do otherwise.  Our prayers in and about such situations are not superior but inferior to the psalms if they do not manifest the psalmists’ thirst for justice and anger at injustice.  As John Goldingay writes, ‘If we do not find ourselves wishing to call down a curse of divine magnitude on some perpetrators of evil, this may reflect our spiritual sensitivity, our good fortune in not being confronted by evil of such measure, or it may reflect our moral indifference.’  Love and forgiveness of enemies should not be invoked to sanction an easy and careless disregard for justice.  The force of Jesus’ command to love enemies is lost if we forget that it presupposes real enemies, and makes no attempt to pretend that they are not enemies.  Love and forgiveness of enemies are authentic only as the costly and difficult step beyond the psalmists’ valid demand for justice.  

Second, the psalmists’ prayer for justice serves in principle to protect their concern for justice from degenerating into vindictiveness, even if it does not always do this in practice.  The prayer is essentially for God to execute justice, and draws the psalmist, beyond feelings of personal vindictiveness, into a desire to see God’s justice prevail.  Admittedly, it is possible for talk of divine justice to be used in the interests of personal revenge.  But the believer who is genuinely open to God in prayer is subordinating his own judgement of the situation to the standard of God’s righteous judgement. . . . 

Third, the referring of the situation to God’s justice is the first step towards love and forgiveness of enemies.  In expressing to God their rage against their oppressors and their desire for vengeance the psalmists are at least submitting and yielding those wishes to God, even relinquishing them to God.  Personal vengeance can be renounced, because one’s cause has been entrusted to the just God who claims vengeance as his own concern (Deut. 32:35-6; Rom. 12:19). . . . In the course of repeating Jesus’ demand for love of enemies—blessing, not cursing them (12:14), not retaliating (v. 17)—he [Paul] forbids his readers to avenge themselves (v. 19a), but does not require them to renounce their concern for justice.  Rather this can be left in God’s hands (v. 19b). This then frees them to treat their enemies forgivingly and to welcome their repentance (v. 20).  Where those in the grip of personal vengeance msut be frustrated, like Jonah, when repentant enemies are spared judgment, those who have committed vengeance to God can promote and rejoice in the compassion by which he at once safeguards and surpasses justice.  They can pray for their enemies’ forgiveness.” (pp. 65-67)