It is going-against a very mainstream - especially Protestant - view of Christianity (and the emphasis of the Apostle Paul) when I say Christianity is not - or is hardly at all - about justice.
Indeed, quite the opposite: the promise of Christ is that salvation comes to all who follow him in love - and that is a massive short-circuit of anything like justice.
My understanding is that God is our loving parents (if regarded simply as our single Father, that makes no difference to my point) - and parents do not naturally raise their children by justice, but by love.
Justice is an abstraction linked to The Law, Judges, prescribed sanctions and the like - and these do not exist in a good family.
(Or, insofar as they do exist, they are expedient, tailored to circumstance and individual, changeable with ages... and so forth - by the end of which the analogy has pretty thoroughly broken-down. We ought not to run our families as if we were a judge disinterestedly interpreting and implementing a set of laws on a nation.)
So - from the perspective arising from what we know of the nature of God and the relations between God and Men - Justice ought not to be the focus of Christianity, not the focus of how Jesus's work is conceptualised.
This is backed-up by the Fourth Gospel - which does Not have a justice-focused account of Jesus's mission. Indeed quite the opposite. Jesus is a deliberate and repeated law-breaker (i.e. breaking the laws of the Jews, including the most profound laws against blasphemy). He repeatedly excuses himself and others from the consequences of law breaking - because there are much more important things afoot; because he is introducing a new dispensation that is Not derived from laws.
Instead; Jesus repeatedly short-circuits the law to aim at what he teaches to be the essence of his twofold message: his own nature as divine, Son of God; and the promise (repeated several times - including at the beginning and end of the gospel) that those who choose to love and follow him (in loving fellowship) through death, will attain to the resurrection of life everlasting, also (like Jesus) as divine Sons of God, dwelling in Heaven.
A justice-centred Christianity is primarily about a religion of obedience to universal laws, about Men satisfying the demands of justice; but that is not correct. Christianity ought primarily to be about following Jesus to life everlasting; about what life everlasting means; and about the fact of love being the basis of creation and salvation alike.
It is not that laws and justice are arbitrary or unimportant - in history or here and now - but that they are expedient. Laws are simplified abstractions hence always incomplete and biased; that laws can be and usually are non-loving 'mechanisms'; and justice is an impersonal procedure, and so on.
In our societies we presumably need laws, but our societies are not (or should not be) rooted in laws; any more than they should be rooted in votes, or money - any other needful expedient. What we are rooted in must stand outside, deeper than, and before laws and justice.
Therefore, it is of particular importance that Christians stop explaining their faith being grounded in legalistic concepts and the demands of 'justice', when explaining to outsiders, among themselves; because this is Ultimately Not True.
In sum; I regard the common focus on justice, when explaining what Jesus did, to be an error - and a dangerous error - because easily refuted by mainstream modernists.
Indeed, a justice-based religion points at Judaism or Islam - much more than it points at Christianity. To focus on justice is implicitly to reject the vital work of Jesus. No matter how hard we try to insert Jesus into the system of divine Justice, the metaphysics of legalism will be working against him.
Justice, for Christians, is therefore a red herring; a misleading distraction from what we really ought to be focusing on; and justice stands in the path of proper understanding.
