As I mentioned in my homily yesterday, I want to give some explanation on how to pray imprecations upon those who show little or no signs of repentance; especially if you wish to use the imprecatory Psalms in your prayers (for a sampling of divinely inspired imprecatory Psalms, you can read Psalms 35, 83, 109, and 137). The imprecatory Psalms are not for the faint of heart; some would not qualify for a "PG-13" rating!
Here is a list of essential factors to consider and practices to engage in.
1) When we pray for "suffering" for an impenitent person, it should not be for the purpose of getting revenge. We must do it with the acknowledgement that it is the means by which God often converts hard hearts and that this is our goal in doing so (if you really just want them to suffer you are in grave sin and should not be praying imprecatory prayers).
2) In this kind of prayer, we can even describe specific suffering if we believe that it is what will lead to the person awakening from their sinful frame of mind (i.e. "God please have him break up with his girlfriend who is leading him to sin"), with the condition that we also acknowledge that God knows which form of suffering is best for that person.
3) Praying for someone who has turned against God to suffer should always include the prayers for someone's ultimate good of conversion.
4) We are never to pray for suffering for those who merely annoy us, or that we do not like, but specifically for those who are fighting against God and what is holy.
5) We must be aware that seeking whatever is necessary for someone to convert, is what it means to love our enemies. The motivator should always be love, not hate, because to pray that God will use whatever is necessary to convert them shows that we trust Him to do what is best and that is part of loving God.
6) If we only pray for nice things to convert someone, we are ignoring the numerous stories of people who came to God because of trial and suffering (I myself am in that list). To leave someone to their own, and offer up no actual prayer of the redemptive efforts of God, is to show hate to these people!
7) We all must be aware that the main reason people have for resisting imprecatory prayers is because they are not steeped in Scripture enough. If someone does not understand the fullness of the redemptive nature of suffering, they will have a hard time with keeping the balance in imprecations. To pray an imprecation is not to hate, but to acknowledge, in love, that God can use pain to bring someone to humbly submit to salvation.
8) Finally, we must keep in the context of our prayers, the fact that we too must be willing to suffer in order to find redemption, and that only by the grace of God can we avoid becoming apostate ourselves.