Social justice and divine justice

Many things can be said about justice. Even when we look at the justice from the point of the Torah, we still can bring numerous verses, commentators from here and there, and when we once immerse in the discussion, we may never get out of it, and even then we may never reach the point where we could say: Now we understood what exactly is incumbent upon us to do in the real time.

Therefore, I will speak shortly and touch only one aspect of thinking and doing justice.
Hashem is just. And he commanded us to pursue justice.
And Hashem is merciful and commands us to be merciful.
Does it contradict each other?
Here I would recall Rav Adin Steinsalz's comment: We need to acknowledge the profound difference between Hashem's and our knowledge. There are many suffering people in the world. Had I looked on this sad picture 'from the point of view' of the Almighty (as we say: hakol letova, roughly: Everything happens for a good reason), I would have let people suffer, I would have said: This is Hashem's will, let it be, I should not intervene. But then, I would be viewed as a cruel man. Rightly? Surprisingly enough, yes. How could it be? Had not I only accepted Hashem's decision?
The answer is to be found in the book of Bereshit, ch. 18-19. Hashem decides to destroy Sdom and Amora and some additional settlements for their wickedness. We would expect Avraham to accept Hashem's just decision. But no! He challenges Hashem's justice. And not only that. Our tradition sees this step as something Hashem expected the righteous Avraham to do!
This means, that on one hand Hashem supervises and rules over the world justly, but he wants us on the other hand to challenge him. Why? Because we do not know what he does know. Because with our limited knowledge and insight we cannot judge in the same way He does. We see just a part of the picture. This enables us, and actually this is our moral imperative, to help the needy, the suffering, to pray for the sick, to help one another. If we cease to do that, we will be portrayed as cruel. Rightly. And maybe even blasphemous. We pretend as if we had the same knowledge and the same power as Hashem does. That is why Hashem tells us to follow him 'modestly', and to emulate His attributes of love and mercy, not the attributes of severity and din (judgement). (It is important to say, that we talk here on the level of an individual, not about what is expected from judges in the courts).

Even if we are the most smart, insightful, logic, reasonable and rational thinkers, we still do not reach a tiptoe of Hashem's knowledge.
Precisely this limitation of human mind enables us to fulfil Hashem's will to be merciful, to be social, to create society, using the formulation of r. Jonathan Sacks, based on the covenant of cooperation.