Forgiveness

When we forgive a debt or an offense or an injury, we don’t require a payment for settlement. That would be the opposite of forgiveness. If repayment is made to us for what we lost, there is no need for forgiveness. We have our due. 
Forgiveness assumes grace. If I am injured by you, grace lets
it go. I don’t sue you. I forgive you. Grace gives what someone
doesn’t deserve. That’s why forgiveness has the word give in it.
Forgiveness is not “getting” even. It is giving away the right to
get even.

That is what God does to us when we trust Christ: “Everyone
who believes in him receives forgiveness of sins through his name”
(Acts 10:43). If we believe in Christ, God no longer holds our sins
against us. This is God’s own testimony in the Bible: “I, I am he
who wipes out your transgressions for my own sake” (Isaiah
43:25). “As far as the east is from the west, so far does he remove
our transgressions from us” (Psalm 103:12).

But this raises a problem. We all know that forgiveness is not
enough. We may only see it clearly when the injury is great—like
murder or rape. Neither society nor the universe can hold together
if judges (or God) simply say to every murderer and rapist, “Are
you sorry? Okay. The state forgives you. You may go.” In cases
like these we see that while a victim may have a forgiving spirit,
the state cannot forsake justice.

So it is with God’s justice. All sin is serious, because it is against
God (see chapter 1). He is the one whose glory is injured when we
ignore or disobey or blaspheme him. His justice will no more
allow him simply to set us free than a human judge can cancel all
the debts that criminals owe to society. The injury done to God’s
glory by our sin must be repaired so that in justice his glory shines
more brightly. And if we criminals are to go free and be forgiven,
there must be some dramatic demonstration that the honor of God
is upheld even though former blasphemers are being set free.
That is why Christ suffered and died. “In him we have redemption
through his blood, the forgiveness of our trespasses”

(Ephesians 1:7). Forgiveness costs us nothing. All our costly obedience
is the fruit, not the root, of being forgiven. That’s why we
call it grace. But it cost Jesus his life. That is why we call it just.
Oh, how precious is the news that God does not hold our sins
against us! And how beautiful is Christ, whose blood made it right
for God to do this.

From John Piper's book, Fifty Reasons Why Jesus Came to Die

Free online book here.