“Vengeance is mine; I will repay.” Hebrews 10.30
Matthew chapter 18 relates Jesus' parable about a servant who is arrested on account of a huge debt he owes to his master. Out of pity the master cancels the debt. No sooner is the servant free than he harangues a fellow servant, who owes him a much smaller debt. The other servants report the outrage to their master, who calls in the ungrateful servant and deals with him accordingly.
To recognise the sheer scale and sufficiency of God's mercy towards us is to realise we have been released from a debt which eclipses anything we could possible owe one another. It is on that basis that Christians are encouraged, nay commanded, to abandon our relatively petty grievances towards other people, leaving whatever retribution they might deserve to God, who is the fairest judge of all. This applies to personal relationships. It does not abrogate the need for national and international systems of justice - otherwise anarchy would reign!
There are three reasons for which a society might justly punish those who have committed crimes. The first is to render those responsible appropriately contrite for their actions; the second is to deter others from similar actions; the third is to express society's repudiation of behaviour which is anti-social and destructive.
In recent years "restorative justice" has become increasingly fashionable. Restorative justice seeks to go a step further than simply punishing the perpetrator, through a process in which they are introduced to their victim in order to understand the impact of their actions and, eventually, apologise and make amends. Evidence is building that such a method reduces the likelihood of re-offending and assist in the recovery of victims. The trouble is that restorative justice relies on the perpetrator being willing to humble themselves and the victim being open to reconciliation - and neither can be taken for granted.
However if one was to apply Jesus' "kingdom principle" of reserving judgment, in recognition that we have been forgiven more by God than we shall ever need to forgive another human-being, then the way is paved for reconciliation in every situation - hard though it may be and often is...