Is forgiveness a spiritual concept that transcends religious boundaries?

Aspects of forgiveness can be applied by anyone religious or non religious. Most of us regularly forgive one another when we offend our friends or acquaintances - once we know that we have offended them and particularly when someone asks us to forgive them or tells us we have hurt them (often we simply say we are sorry). This alone is helpful, but sometimes the thing we need to forgive is so grievous or the person we want to forgive us refuses or we need to be forgiven of things that only we know about ourselves.
In Christianity radical forgiveness is a principle that when we apply it in its fullness it produces great fruit and results in increased human flourishing. It involves two equally important dimensions. First, Christians are told to forgive offenses of people who have not even realized they need forgiveness and have not even asked. This is both for our benefit and the benefit of those we forgive. We release them from a spiritual burden and release ourselves from carrying the pain. I always say it frees us from "hooks that can snare us" and diminish our lives. This kind of radical forgiveness was modeled by Jesus who forgives those hanging him on the cross. My pastor once said that unforgiveness was like drinking poison and hoping the other person dies.
But the other side of forgiveness in Christianity involves seeing and confessing those things in our lives that we know are wrong (bad attitudes, sinful thoughts, undone tasks). We repent to God and He forgives us because of the work of Christ on the cross (a spiritual transaction). But not only that, He also promises then to cleanse of us our iniquities (the motivations that caused the sins). Gradually (but sometimes immediately) the wrong motivations we have confessed begin to lose their strength and power over our lives as God cleanses us and we are continually freed of the burden. These are clearly spiritual transactions.
While anyone can use some of the more common rules of forgiveness, without God forgiveness is less full and less effective.