Have you noticed that the justice system (of western countries anyway) is becoming less and less about providing justice? The concept used to be that if you committed a crime you should be punished in accordance with the severity of the crime. The justice system was about acting on behalf of the community to sentence criminals to fair punishment, eg a specified term in prison. In order to justly punish a person for what they did, the full term must be served because no amount of good behaviour can make up for or blot out what was done before.
Now though, the sentence given by a judge does not mean the criminal will serve that sentence. Good behaviour and a low risk of reoffending will mean criminals are released before they have served the full sentence. The focus is on preventing reoffending not on providing a just punishment for the crime committed.
I wonder if this changed concept of justice makes it difficult for people to understand God’s justice. People think that their good behaviour makes up for or cancels out any sin, in the same way that criminals are let off their full sentence if they’re good and aren’t likely to do it again. The idea that the only way God can be just is to punish in full all sins committed doesn’t fit with the way justice is served in the community.