I think I'm a horrible person, in that, I'm too generous. If a person messes up, if they apologize for whet they did, I'll decide whether or not they're really sincere and let that decide my actions, but inside I always forgive. It's put me into nasty situation after nasty situation, because I believe that everyone has a right to try to be better, and I often make possibly unforgivable mistakes myself.
I follow the Golden Rule with this, and actually most other things, although I am atheist and its religious application is irrelevant to me.