The concept of justice deals with what is fair, right, equitable, and moral.
When someone is wronged, they demand justice, be it in the form of an apology, remuneration, or punishment. However, when we do something wrong, we prefer mercy instead of justice.
The word justice occurs several hundred times in the Bible, mostly in the Old Testament. Although it also appears in the New Testament, the focus there is more on God‘s mercy and grace and not so much on God’s justice.
Total justice precludes the option for mercy, whereas complete mercy rules out justice.
Paradoxically, God is a just god, but is merciful to those who follow him.