EDIT:
Yikes, I left out the most important part of my answer!
I don't believe that forgiveness is necessarily a compact between an individual and a person(s) who harmed that individual.
It's important to understand that people who maliciously hurt you have likely hurt other people as well - and they will likely hurt other people in the future. This is particularly true of organized crime and the political arena.
So if I'm stabbed in the back by a derelict school official who ruins the lives of thousands of children, then forgiving that person and walking away would be an extraordinarily selfish act. I believe people have a duty to hold other people accountable.
(Original answer)
Wow, great question!
As a long-time political activist, I've been struck by the incredible hypocrisy. There are very powerful and evil people who hurt other people 24/7. I'm talking about the government, media, corrupt unions, corrupt school officials, etc.
How can it be OK to sentence a bank robber who steals $1 million to prison, but a politician who cheats millions of people out of billions of dollars never pays his dues?
As a lone activist, all I can do is expose them and maybe call them names. But when I do this, I'm smeared for my lack of "civility."
The Lord's Prayer doesn't have any influence over me, because I'm not a Christian. I respect some Christian values, like forgiveness, but I also believe in accountability.
It's worth noting that Jesus wasn't above holding people accountability. One of my favorite Bible stories was the story about Jesus attacking the money changers. (I like to think of Jesus as the first socialist - fighting capitalists to boot!)
I think the best illustration of my personal philosophy is Che Guevara. He's famous for his compassion, yet he's also reviled because he fought on the battlefield and executed prisoners in the wake of the Cuban Revolution.
In fact, there's no conflict at all; he demonstrated his compassion by doing what needed to be done. I have far more contempt for teachers and parents who look the other way while their children are being abused in derelict schools.
In summar, I take the Lord's Prayer with a big grain of salt.