Why should we go to them, shouldn't they be coming to us? Well, yes, they should, but the Lord commands us to go to them just as He commands them to go to us and confess and repent, so ideally both parties should be on their way to each other right away. It rarely works that way though, so the Lord says, we're to go to them if they haven't already come to us. It helps if we understand the Lord's reasons behind His commands. His command to us that He tried to drill into our heads over and over is to love one another, and for unity in the body of Christ, so this is all about reconciliation. For the body of Christ to work the way the Lord intended, there can't be hard feelings between the various members of it. I'm not talking here about the members of a local church, but of the whole body, which is all who've been saved.
That bring up another question...what about those who aren't saved? What do we do then? The Lord never forgives us until we repent and then we become saved. Before then we really don't understand about sin, repentance or forgiveness and what it really means. So with the unsaved, we can only offer them a shallow portion of what we give each other when we forgive. But, in so doing, we're at the same time giving them an example of what being saved is all about and it can give us a great opening too to talk to them about the real deal...about salvation in Christ. We can explain to them that we can forgive them for ourselves, but that we can't forgive their actual sin for only God can do that, and for that they need to recognize that they need a Savior, etc. We can explain that when we forgive, it also means we won't bring the sin up to them, ourselves or others ever again or use it against them in any way, just as the Lord does for us when He forgives us and saves us. This can plant many good seeds the Lord can use to bring them into His Kingdom.
But, do we have to forgive someone who's not saved? Yes, God still commands us to forgive them. His reasons for this are similar, for we're commanded to love them as well as other believers, though for a different reason. First because we don't know that they won't one day be a believer and our brother or sister in Christ. Only the Lord knows that. Therefore the Lord doesn't want things coming between us and them that might stand in our way if/when they do become a believer. Secondly, He wants us to represent Him to them, so we're literally to be Him to them, act as He would, speak as He would, forgive as He would. Of course this is to hopefully bring them into His Kingdom one day. The Lord knows that because they are unbelievers though that forgiveness and reconciliation won't always be possible. That's why He tells us regarding unbelievers, Romans 12:18 —If it is possible, as far as it depends on you, live at peace with everyone. * Therefore we're to do all we can to live at peace with them.
All of this can be difficult but it seems the most difficult part is that we usually don't "feel like" forgiving them, whether they're saved or not. Yet, the Lord never tells us to do something that's not possible, so how do we deal with this? First we have to realize that our feelings have absolutely nothing to do with it. Seriously, they don't! We often do things we don't feel like. Every morning I used to have to be up no later then 6 so I could be at work by 7. When that alarm clock went off, I sure didn't feel like getting up, but I did, and I surely didn't want to go to work, or feel like it, but again, I did. Day after day. It's the same thing with forgiveness.
I never asked anyone if I'd truly gone to work that day since I hadn't felt like it that morning when I'd awakened, and yet we constantly find ourselves asking if we really forgave someone since we didn't feel like it when we did it and our feelings for them hadn't changed. The answer to that is simple. Of course we forgave them! (assuming we forgave the way the Lord forgives us anyway)
Part of the reason our feelings about the person haven't changed though is usually because we didn't really forgive them the way the Lord does us. We left out the part about not bringing the matter up to them, to others, or even to ourselves again. That's the clincher! And how in the world do we do that???? Again, the Lord tells us how. Obviously the Lord can't and doesn't really "forget" our sins. He knows everything, and if He literally forgot them, then He wouldn't know everything and that contradicts His Word. What He means is that He doesn't think of our sins; He doesn't dwell on them, He doesn't hold them against us, even when we later repeat the same sin again. And that's exactly what He requires us to do. He calls it "taking our thoughts captive and making them obedient to Christ." (2 Corinthians 10:5 ) There is a short teaching about this subject here if you need to know how to do this: Taking Thoughts Captive it does take self discipline, but it's what the Lord expects of us and it will change us to be more like Christ in more ways then I can begin to count here. Basically, what it means is that whenever we find ourselves beginning to think about (or speak about) what happened, we literally stop the thoughts/words before they go any further, reminding ourselves of our promise and that the Lord has done this many times for us. Since we have broken our promise, we then need to ask the Lord's forgiveness. Because of our sin nature, at first we'll find ourselves thinking of it quite often or wanting to think about it anyway, so we'll constantly have to take those thoughts captive and replace them with God's Truth as described in the thread I mentioned. The more we do this, the less often it will happen, until eventually we will find that our feelings will begin to reflect the feelings of our Lord instead of our old sin nature. Eventually those old feelings will be entirely replaced with those of love from our new nature that's like the Lord. This is what makes true forgiveness and reconciliation really possible.
So remember, our feelings, don't matter as far as whether or not we can forgive or have forgiven. They will eventually begin to reflect the truth though the more we keep our thoughts in line with the Lord's when the matter does come to our attention.
When we forgive someone, it's a big deal, and something major happens in the spiritual realm and for the person being forgiven as well as for us. Giving or receiving forgiveness is not something that should ever be done lightly or without prayerful thought, which it often seems to be these days. Forgiveness is something we do out of love for our Lord to be obedient to Him; so we offer the offender a gift...not because they earned it by repenting, but because we love the Lord.
It's very different from the world's way of "apology". When people apologize, they don't have to confess any sin or even admit why they're really sorry. They could simply be sorry they got caught or that their reputation might suffer or for other consequences of what they did. They don't have to recognize that God has anything at all to do with it even. They're not promising you anything at all either. That doesn't mean however that we should never say we're sorry, but we should be aware of the difference between the two.
As I said at the start, I realize this doesn't cover anywhere near all the questions concerning forgiveness and forgetting concerning both the saved and unsaved, but I hope it gives at least a glimpse of how the Lord wants us to forgive and why. And of course, I hope it helps others as it has me in my own life.