How to forgive

To err is human, to forgive divine. So goes the saying. Why divine? It is divine because it is hard to do, almost impossible where our emotions run high. When we are angry with someone, when we hate someone who has done us harm, we would have to be angels to forgive him (or her).
In my experience, I think this has to do with a sense of injustice. We judge the person, we condemn him, and we want him to pay for what he has done. The only trouble with this approach is that the only person suffering here is ourselves.

Judge not, that ye be not judged. For with what judgment ye judge, ye shall be judged: and with what measure ye mete, it shall be measured to you again. Mathew 7:1-2

To hate, judge and condemn the other person we must first fill ourselves with hate, anger and negative energy. Our thoughts are creative and by harbouring them we bring about, we manifest the negative situations we condemn in the other. From 'The Power of your Subconscious Mind' by Dr Joseph Murphy:

This means that in applying standards and criteria to others, you create those standards and criteria in your subconscious, which then applies them to you. Once you know this law and understand the way your subconscious mind works, you will always be careful to think, feel, and act right toward others, for in doing so you are creating a situation of right action, feeling, and thought toward yourself.

In other words it is in your own best interest to forgive. You forgive for yourself. You forgive in order to let go of the negative energy that is poisoning your subconscious and your life. Anyone who has genuinely forgiven knows the liberating feeling that comes with it.
When you forgive, you are not saying that what that person did to you was right. You are not agreeing with that person’s actions. You are simply letting go of the negative emotions you feel for that person, for your own good.
To let go of those negative emotions we must replace them with other positive emotions. Whenever we think of that person, we must replace any hateful emotion by a positive thought. Dr. Murphy suggests this affirmation:

I fully and freely forgive (the name of the offender). I release him (her) mentally and spiritually. I completely forgive everything connected with the matter in question. I am free and he (she) is free. It is a marvellous feeling.

Another major obstacle to our ability to forgive, I have found, is our inability to understand the other person and what has happened. How could that person do such a thing? Marcus Aurelius, the Roman emperor and philosopher, offers us this advice (from 'The Meditations of Marcus Aurelius' translated by George Long):

Whatever man thou meetest with, immediately say to thyself:
What opinions has this man about good and bad? For if with respect to pleasure and pain and the causes of each, and with respect to fame and ignominy, death and life he has such and such opinions, it will seem nothing wonderful or strange to me, if he does such and such things; and I shall bear in mind that he is compelled to do so.

When we understand ‘where a person is coming from’ we will have more appropriate ‘expectations’ and we will be better disposed to be tolerant. This is another way of saying, to understand all is to forgive all. And if we are able to understand all, it will be easier for us to forgive.
But we should not wait to understand all before forgiving. This reminds me of the Buddha's parable:

It is as if a man is hit by a poison arrow. His friends hasten to the doctor. The latter is about to draw the arrow out of the wound. The wounded man however cries: `Stop, I will not have the arrow drawn out until I know who shot it. Whether a warrior or a Brahmin, or belonging to the agricultural or menial castes... his name and to which family he belonged...'

Such a man would be a fool not to have the arrow pulled out immediately in order to save his life.
Similarly, it is more important for us to forgive now to get the poison out of our system, than to wait until we understand the situation more completely.
Even if we cannot always ‘understand all’, we can understand that if we could understand all, we would forgive all. Therefore, we will not go far wrong by forgiving now, ‘on faith’.
God always understands all and he always forgives all. If we do the same, wouldn't that be divine?