We all have people that we need to forgive. It is impossible not to, simply because everyday we find reasons to hold grudges. Reasons to be be angry at our family, friends, co-workers, and even that guy who honked at you all the way to work. And if we are not careful, these feelings of anger can grow, and take over our hearts. Soon we aren't only angry, but we want them to pay for their actions. We want revenge.
I think one of the best examples of this is People's Court. If you have ever watched it, I am sure you have seen someone who is only there to ruin the other person's reputation. They bring out allegations that are completely irrelevant to the case, trying to make the person look bad, and trying to ruin them for what they have done. Instead of justice, they focus only on revenge, what they feel the other person deserves.
One woman summed it up quite nicely, after a nasty law-suit with her "ex-friend," by saying, "No. She doesn't deserve my friendship... she doesn't deserve my love." So many times life-long friends allow themselves to be separated; not over the $300 lawsuit, but by their feelings of anger and hatred.
Some of these very same people also claim to be proud Christians, and yet they have forgotten that we don't deserve God's love. Just like their friend turned his/her back on them, we have turned our backs on God... many, many, many times. We have allowed our sins to separate us from God, and only by His mercy and His grace were we brought back to Him.
Just as God has forgiven us, He tells us we need to forgive others. He tells us that we have no right to hate others, because He does not hate us (and we have committed far worse crimes against Him, than they have against us). He says that no matter what their debt to us is, our debt to Him is greater, and yet He has forgiven us (Matthew 18:21-35).
As Christians we can not let our anger get the better of us, nor can we allow it to grow to hate. We cannot be like the unmerciful servant who refused to forgive his debtors, even though his debt was forgiven. We cannot hate our brother, and claim to love God, because God is Love (1 John 4:16). He tells us that if we love Him, we will obey His commands, and He commands us to love each other (Leviticus 19:18).