Who Would Say "God Is Just"?

Is it true that it's always those who live in comfort would assert "God is just"? I don't mean that all people living in comfort would believe this notion but I can hardly imagine those who live in misery would think this way.
Just wondering.

"God Is Just" - A Truth Or An Excuse Of Selfishness

I say "God is just" is another convenient excuse for practice of selfishness, because if God is just, why do we have to help the poor? That's God's will!

Another argument for religious people on this subject would be, letting some people to be poor so others can help them is one of God's lesson, or "design", in order to let people to learn kindness. Really? How about those helpless, those who died in pain, suffering without cure? And is the lesson of kindness really worth thousands, millions sacrifices of life? Would those who were burned alive agree that their excruciating pain (actually I doubt "excruciating" is enough to describe how they felt) was a means used by God to educate others? If so, I would say this God is either unspeakably cruel, or incredibly dumb. Or both.