I post this bold statement under the assumption that you know that there is no such thing as choice. This is an indisputable fact if you have studied the workings of psychology and is a different topic. I'd be happy to clear that up on another thread if enough people are confused.
The idea here is: since there is no choice, no action could possibly be a person's fault. There is no such thing as an "evil person" or an "evil act." What reason, then, should you have for not forgiving someone when your actions and theirs are a result of chance? Of bad luck?
Your genes and experiences have brought you to a place where your paths intersected in a negative way and it was by chance that you were wronged.
Now, what reason is there to hate or hold a grudge against another human being? We are all victims of chance. We have the same amount (none) of control over our actions and it is my personal interpretation of responsibility that we all work together to make a peaceful community on this rock we call earth that stresses the importance of universal love.
We have no choice. Why hate? Why hold a grudge?
Hate hurts. Hate kills. Hate is physically unhealthy. Our appeals to those who wrong us should be through reason, which is balanced and accessible to those who don't share our personal bias.
I'm suprised that I don't have more to rant about, but I feel like once I've put the thought there, it is rather self-evident.
I'd be happy to debate in order to clear up my position. Thanks for reading!