Justice is a difficult and contested word. What one person considers just, another may consider unjust. It’s very important that we distinguish between our human ideas of justice and God’s justice. Our task is to make God’s justice our starting point.
A biblical understanding of justice needs a basic premise: our world has gone terribly wrong and needs to be put right. The word translated over 200 times in the Old Testament as justice is mishpat. Put simply, it means rectifying justice – giving people what they deserve and it is used both in the contexts of legal punishment and taking care of the most vulnerable in society.
Alongside mishpat, we need to hold tsedeqa. Tsedeqa tends to be translated as righteousness – a word that we can unhelpfully associate with self-righteousness. A better understanding of righteousness is right relationships. To be righteous is to be in right relationship with God, with others, with ourselves, and with creation. Crucially, tsedeqa can also be translated as justice. And so, we have this picture of justice not simply as a tit-for-tat system of crime and punishment, but a full, whole society where relationships between God, people, and all of creation, are made right.
In the New Testament, the Hebrew tsedeqa is carried over into the Greek dikaiosyne word group, from which we get words like justice, justification and righteousness. God’s justice and righteousness are essentially the same thing – to be righteous is to do justice.
Working out the relationship between justice and mercy is important. Through the Old Testament, in places like Micah 6.8, (act justly, love mercy, walk humbly) justice and mercy are held together. The word translated as mercy is hesed – it means much more than mercy – describing God’s faithfulness and covenant love – often linked to the tangible protection that God offers to the worst off in society. This paradox of the justice and mercy of God’s character is most emphatically seen on the cross. The cross is not simply about forgiveness, it is God putting right an unjust world. Both perfect mercy and perfect justice. Only the creator of the universe can put to right all that is wrong in human beings and in the world. Only the creator can bring about perfect justice – right relationships in every dimension – in the world he has created. He has done so in Jesus, and what God has done in Jesus is what he will do for the entire creation.
Finally, it is worth noting that the bible compels us not so much to reflect on justice as to do justice. God’s justice is not abstract or impersonal. God’s justice is personal and active – more like a verb than a noun – putting right what is wrong. Again, we see the integral relationship between God’s justice and mercy – love shapes the content of justice. We see throughout history how easily those who fight for justice can become perpetrators of injustice. Justice divorced from self-giving love, justice without the will to embrace both victims and oppressors, falls short of the biblical vision of justice.
So, our definition of justice needs to hold together mishpat, tsedeqa and hesed. God’s justice, is about putting to right all that is wrong in creation; mending all that has been broken by sin. This justice is active, it means struggling against injustice, it is shaped by love, and its goal is a world of righteousness – right relationships in every dimension – between God, people, and creation. That world of perfect justice is something that only God can bring about. He has done so in Jesus, and he will do so in the new creation age to come. By grace, our task is to join in with that mission of putting right what is wrong – pointing back to the cross and forward to new creation.
 Timothy Keller, Generous Justice: How God’s Grace Makes Us Just (London: Hodder & Stoughton, 2010), 3-5
 Fleming Rutledge, The Crucifixion: Understanding the Death of Jesus Christ (Grand Rapids: Eerdmans, 2015), 133-4
 Njongonkulu Ndungane, ‘Loving Mercy: Restoring Personhood, Restoring Society’, in Marijke Hoek and Justin Thacker (eds.), Micah’s Challenge: The Church’s Responsibility to the Global Poor (London: Paternoster, 2008)
 Rutledge, The Crucifixion, 114; Miroslav Volf, Exclusion and Embrace: A Theological Exploration of Identity, Otherness, and Reconciliation (Nashville: Abingdon, 1996), 298
 Rutledge, The Crucifixion, 124; Tom Wright, Surprised by Hope (London: SPCK, 2007), 103
 Volf, Exclusion and Embrace, 217
 Rutledge, The Crucifixion, 134
 Volf, Exclusion and Embrace, 220-3