The God of Justice and Mercy

What is the relationship between justice and mercy? How do we understand God's heart of mercy, and how does that character inform our actions, our obedience, our walk, our talk of faith? Where does the justice of God come into play? How are we to think about His eternal justice and the terrible reality, that hell is for all who pursue evil? And most importantly, how are we to reconcile these seemingly conflicting attributes without diminishing either? For both are scripturally true, and both are present in this passage.