When we say that we believe that God is 'just', what do we mean? What kind of justice are we talking about? For the most part, I think that people assume retributive justice (where God punishes those who've done wrong) or sometimes restorative justice (where we try to appease God by making amends for wrongdoing). From a social justice perspective, we might be better off considering distributive justice, where the primary concern is equity - a fair go for all.
Distributive justice is demonstrated in the legal structures of the Jubilee Year, where land is periodically (every 50 years) redistributed amongst the people so that those whose family holdings have been diminished over time have a chance for a fresh start. I'm on the verge of going to Zambia this week and thinking about the grossly uneven distribution of resources throughout the world. If we claim to be followers of a God of distributive justice, we must be committed to addressing such outrageous inequities.