To excuse what can really produce good excuses is not Christian charity; it is only fairness. To be a Christian means to forgive the inexcusable, because God has forgiven the inexcusable in you. This is hard. It is perhaps not so hard to forgive a single injury. But to forgive the incessant provocations of daily life–to keep on forgiving the bossy mother-in-law, the bullying husband, the nagging wife, the selfish daughter, the deceitful son–how can we do it? Only, I think, by remembering where we stand, by meaning our words when we say in our prayers each night, “Forgive us our trespasses as we forgive those who trespass against us.” We are offered forgiveness on no other terms. To refuse it means to refuse God’s mercy for ourselves. There is no hint of exceptions and God means what He says.
… C. S. Lewis (1898-1963), “On Forgiveness,” in The Weight of Glory