Justice and Mercy
How can God be just and at the same time merciful? How can God show mercy to wicked sinners and remain just and holy? A just judge would be declared unjust and unfit for his role if he allowed the guilty to go free. We would expect the judge to be just by judging the guilty, and the guilty we would expect to pay the penalty for their guilt. Our expectations are legal. Our expectations of mercy are for the not guilty. The guilty should bear the weight of our legal demands and we who are 'innocent' should receive our deserved mercy by watching the guilty get their justice while we get our freedom from their wickedness.
But we have not the thoughts of God. The Belgic Confession explains in Article 20 entitled, The Justice and Mercy of God in Christ:
We believe that God-- who is perfectly merciful and also very just-- sent his Son to assume the nature in which the disobedience had been committed, in order to bear in it the punishment of sin by his most bitter passion and death. So God made known his justice toward his Son, who was charged with our sin, and he poured out his goodness and mercy on us, who are guilty and worthy of damnation, giving to us his Son to die, by a most perfect love, and raising him to life for our justification, in order that by him we might have immortality and eternal life.
The thoughts taken captive to Christ by faith then consider self dead to sin and God's condemnation, and alive to God in the resurrection and justification of Christ. God is just and the justifier of sinners who live by faith in his satisfied justice and mercies in Christ. Sin is paid for in Christ's death and life is lived in Christ's resurrection. This is the Father's love in justice and mercy.