Conditional forgiveness is a topic addressed by many others including Jay Adams, Lig Duncan, John MacArthur, Ken Sande, John Piper and Justin Taylor. Here is a survey of what others have said about conditional forgiveness.
Jay Adams on Conditional Forgiveness
Jay Adams argues without qualification that forgiveness is conditional. Notice Adams’ balance in stressing that Christians are obligated to try and bring an offender to repentance.
What shall we say then? It is clear that forgiveness-promising another never to bring up his offense again to use it against him – – is conditioned on the offenders willingness to confess it as sin and to seek forgiveness. You are not obligated to forgive an unrepentant sinner, but you are obligated to try to bring him to repentance. All the while you must entertain a genuine hope and willingness to forgive the other and a desire to be reconciled to him or her. Because this biblical teaching runs counter to much teaching in the modern church, it is important to understand it. Such forgiveness is modeled after God’s forgiveness which is unmistakably conditioned on repentance and faith.
Ligon Duncan on Conditional Forgiveness
This is a question that many Christians have never thought through. I think that Christians who have themselves harbored unjustified bitternesses and have been unforgiving in places and in ways that they should have been forgiving, often when they are confronted with and gripped by the radical teaching of Christ on forgiveness, out of sorrow for their own sin, read Jesus’ teaching on forgiveness in such a way that they understand it to mean that forgiveness is an automatic obligation in every circumstance, irrespective of the repentance of the other party. And, again, I think that that is a mistake. I believe that forgiveness always has in view reconciliation, and reconciliation is always two-sided. So if there is not a repentance corresponding to a forgiveness, then very often there is an impossibility of reconciliation. I think that whatever we think about forgiveness, forgiveness is a component to what is a larger picture, and the larger picture is reconciliation. And reconciliation is necessarily two-sided. Consequently, I think it is important for us to talk about both forgiveness and readiness to forgive. There may be circumstances where a reconciliation is impossible, but a readiness to reconcile can still be present with a believer. Consequently, I would want to make that distinction when I was counseling a believer who was in a circumstance where there was not a present possibility of reconciliation of the relationship. Instead of telling them that they need to forgive or they will become bitter, I think I would rather say that you need to be ready to forgive and not to be captured by your bitterness. http://www.reformation21.com/Upcoming_Issues/Forgiveness_Roundtable/354/.
John MacArthur on conditional forgiveness
John MacArthur argues that for small matters there are times when forgiveness is unilaterally and unconditionally granted. But, MacArthur also clearly argues that conditional forgiveness is at times appropriate:
It is obvious from Scripture that sometimes forgiveness must be conditional . . . There are times when it is necessary to confront an offender. In such cases, unconditional forgiveness is not an option. These generally involve more serious sins- – not petty or picayune complaints, but soul-threatening sins or transgressions that endanger the fellowship of saints. In his book, Forgiveness, (Crossway), 122-128.
Ken Sande on Conditional Forgiveness
Ken Sande agrees that there are times when a matter should be overlooked. And, he also agrees that in most ideally forgiveness should follow repentance. Sande pictures forgiveness as a two stage process. In his words:
When an offense is too serious to overlook and the offender has not yet repented, you may need to approach forgiveness as a two-stage process. The first stage requires having an attitude of forgiveness, and the second, granting forgiveness. Having an attitude of forgiveness is unconditional and is a commitment you make to God . . . By his grace you seek to maintain a loving and merciful attitude toward someone who has offended you . . .
Granting forgiveness is conditional on the repentance of the offender and takes place between you and that person . . . When there has been a serious offense, it would not be appropriate to [make the promises of forgiveness] until the offender has repented. (See his The Peacemaker, pages 77-79, and 210-211.
Justin Taylor on Conditional Forgiveness
“Love your enemies” is something that we should do at all times and in all places. It is modeled after God’s love for his enemies, whom he loves even when they are “unjust” and “evil” (Luke 6:35). At the same time, our forgiveness of others is likewise modeled upon God’s forgiveness of sinners, whom he forgives conditioned upon their repentance. God does not forgive apart from repentance; neither should we. In major offenses, we are not to forgive the unrepentant.
In the event of a tragedy that involves the loss of human life brought about by wanton human sin, it is therefore wrong for Christians to call upon immediate forgiveness in the absence of repentance. Such a call both cheapens and misunderstands the biblical doctrine of forgiveness.
See Justin’s post on conditional forgiveness “Is Forgiveness Always Right and Required?”
John Piper on Conditional Forgiveness
One last observation remains: forgiveness of an unrepentant person doesn’t look the same as forgiveness of a repentant person.
In fact I am not sure that in the Bible the term forgiveness is ever applied to an unrepentant person. Jesus said in Luke 17:3-4 “Be on your guard! If your brother sins, rebuke him; and if he repents, forgive him. And if he sins against you seven times a day, and returns to you seven times, saying, ‘I repent,’ forgive him.” So there’s a sense in which full forgiveness is only possible in response to repentance.
But even when a person does not repent (cf. Matt. 18:17) we are commanded to love our enemy and pray for those who persecute us and do good to those who hate us (Luke 6:27).
The difference is that when a person who wronged us does not repent with contrition and confession and conversion (turning from sin to righteousness), he cuts off the full work of forgiveness. We can still lay down our ill will; we can hand over our anger to God; we can seek to do him good; but we cannot carry through reconciliation or intimacy.
Update (6/27/12): See also this post on a primer by A.B. Caneday which argues for conditional forgiveness and Kevin Lewis of Biola University: Should forgiveness be conditional or unconditional?
Update (7/5/13): Douglas Wilson writes:
“We cannot forgive those who are defiant, however much we might like to. Because forgiveness is a transaction, if someone steals your car, you can’t run down the street after them, yelling out your forgiveness” (For a Glory and a Covering, p. 95).
“But you can have a heart full of forgiveness, full to the brim, ready to overflow the moment repentance appears. Until that happens, there is no forgiveness. We need to distinguish forgiveness in principle and forgiveness accomplished” (For a Glory and a Covering, p. 95).
I’m always amazed at the response (notice that there are 57 comments and climbing on Tim Challies blog) generated when it is argued that biblical forgiveness is conditioned on repentance. . . .especially, when it is not a novel position.
 A Roundtable Discussion on Forgiveness: Derek Thomas Interviews Ligon Duncan and Justin Taylor, (Reformation 21, accessed October 23 2007); available from http://www.reformation21.com/Upcoming_Issues/Forgiveness_Roundtable/354/.
 John Piper, As We Forgive Our Debtors: What Does Forgiveness Look Like(Desiring God Ministries, 1994, accessed September 19 2007); available from http://www.desiringgod.org/ResourceLibrary/Sermons/ByDate/1994/868_As_We_Forgive_Our_Debtors/.