Psalms 85:10 Mercy and truth are met together; righteousness and peace have kissed each other.
Romans 3: 24 Being justified freely by his grace through the redemption that is in Christ Jesus. 25 Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God; 26 To declare, I say, at this time his righteousness: that he might be just, and the justifier of him which believeth in Jesus.
So, basically in a nutshell, wherever sin and wrongs are committed, someone has to pay for it. Persons who are unrepentant might not pay right away, but sooner or later, justice will be administered because those two characteristics of God could only exist as an inseparable whole. In trying to understand how justice and mercy work together, one of the most important things for folks to remember is that God is the Sovereign owner of everything and everyone on the planet, and indeed, in the entire universe, and thus, His administration of justice must be understood within that context.
In other words, it remains God’s sole prerogative to show mercy in some circumstances or to administer justice as He sees fit. He reserves the right to do this as Sovereign owner. This perspective should solve many of the difficulties persons experience, when trying to figure out the reasons why God did such and such in any given situation.
Psalms 24:1 The earth is the Lord's, and the fulness thereof; the world, and they that dwell therein.
May The Lord add His blessing to the study of His word. God bless!