The responsorial psalm today "Remember your mercy, Lord" is a perfect example of how sometimes we say to God what we need to hear. After all, do we think God ever forgets his mercy? The first reading as well sings the greatness of God's mercy.
The gospel then turns to us and challenges us, as beings created in the image and likeness of God, to imitate the great mercy of God — or else.
With the story of the servant who is forgiven, but then refuses to forgive, we get a glimpse of what may be the greatest danger to our salvation, the unwillingness to forgive.
When we hear the phrase "mortal sin", our minds immediately jump to the lurid. Yet, time and again we see those sins forgiven. Those who are most severely punished, as in today's gospel are those who refuse to reflect the mercifulness of God.
Some say they want to forgive and can't. To them I would ask simply, what do you get out of holding on to that hurt? We only hold on to those things from which we derive some benefit.
As God's children, we must daily reflect the love and also the mercy of God.