The following things are said to be forgiveness.
One, it is the letting go of the desire/intention to see the offender suffer the same evil as he or she has done to you or to a loved one. You cease wanting to hurt them back. This is an emotion and it can be slight or very severe.
Two, it is letting go of the anger. Anger can range from being nearly harmless to you when it is weak but very destructive to you when it is strong.
Three, it is letting go of the feelings of hurt. Again these feelings can hurt you a tiny bit but if they get stronger the more harm they will do to you.
Four, it is an act of love for the one who wronged you. In doing this, you prove your own dignity. You are not going to reconcile with them necessarily but you are going to help them if they need help.
It is cautioned that forgiveness does not mean condoning or letting the other person away with it - if there is a real risk of them doing further harm. They need to be deterred. Others need to be protected. This is what people mean when they say forgiveness does not mean opposing justice, but upholding it.
But that assumes you are in a big enough community with functional criminal justice. Many of us are isolated in our families. What if it is you and two others on a desert island and one of them is evil? Forgiving in some cases does mean letting the person away with it to do it again.
One, two and three are not forgiveness at all. They are feelings. If you have bad feelings towards someone, you simply can't just switch the feelings off. Having the feelings does not mean you have failed to forgive.
Only four is the essential or main thing.
If you let go, then let go for your own sake. Forgiving will be three times harder if you are expected to do it for God or Jesus or somebody else. Religion puts a burden on people.
Forgiveness is not necessarily loving. You can forgive a person because you want to get back at them by coming across as better than they are and as if what they did to you can't hurt you any more. Such forgiveness is really revenge in the garb of forgiveness. But it is very healthy and good for you. It is better than the saccharine and flowery alternative the Church and Jesus Christ require of you.
It is possible that this passive-aggressive "forgiveness" is the main form or plays a significant role, subconsciously, when anybody forgives.
The forgiver has an advantage - nobody sees if they really do forgive and for good reasons. And they can forgive today and reverse it tomorrow.
Jesus and Catholics priests say they forgive sins. What if they actually cannot?
If a sin is grave and you get forgiveness from a non-existent God or non-existent forgiveness from a real God that is very serious. Forgiveness needs to be real. It needs to be truly granted by a real being. Otherwise it is just an insult to the victim of the sin. And to the person asking for mercy.
A fake fresh start is a fake fresh start. Only real forgiveness can support a new beginning.
Forgiveness means you judge the person as evil and then you bestow mercy - you refuse to hate them or punish them as they deserve in order to give them a new beginning. Only a real being who really exists and really forgives can do these these things.
If I ask God to forgive me for murdering a baby and I am not forgiven at all then that trivialises forgiveness and its consequences. Forgiveness involves a relationship. No relationship no forgiveness.
Here is a list of evils that happen if you wrongly think you mean your prayer for pardon. If there is a God who has not forgiven you. Or if there is no God to forgive at all.
False security: You may stop self-examination or repentance, thinking things are settled when they are not.
Moral stagnation: Believing forgiveness is granted without sincerity can remove motivation to change harmful behavior.
Self-deception: It trains the habit of convincing yourself you’re right with God when you’re avoiding truth.
Hardened conscience: Repeated insincere prayer can dull guilt and moral sensitivity over time.
Broken relationships: Assuming divine forgiveness may replace the hard work of making amends to others.
Spiritual drift: Treating forgiveness as automatic can weaken reverence, humility, and accountability.
Delayed growth: Real transformation often begins with honest recognition of fault; skipping that slows maturity.