Intersection of Justice and Forgiveness

What a difficult question. My answer is this: Do what is beneficial. If someone needs punishment to learn a lesson, give them punishment. If the person is truly repentant, offer forgiveness to teach them grace. If others need to know that punishment will follow particular actions, proffer punishment. In each scenario, try to find what will do the most good. In a sense, we leave feelings out of it and try to look objectively at the situation and make a good decision. Of course, this is extremely easy to implement, assuming your God.