I think that part of the answer lies in the fact that God has given each of us a choice. We choose to follow His guidelines for life, or we choose to ignore them. And almost always, those choices affect more than just us as individuals. The ripple effect leads one sin to cause a LOT of misery, suffering or strife for those around us. Those choices are man's, not God's.
But there's also another side. What about this?
"God is not unjust; he will not forget your work and the love you have shown him as you have helped his people and continue to help them" Hebrews 6:10He is watching the work we do for others. Now I don't want to suggest that I'm advocating an entirely social gospel but there are definitely directions in God's Word about helping others - both friends and enemies (see Galatians 6:10, Ephesians 4:32, Luke 6: 27-36). Think of the Good Samaritan. Think of Dorcas and the early church elders. We don't earn our salvation but our salvation does bring an obligation.
"Religion that God our Father accepts as pure and faultless is this: to look after orphans and widows who are suffering and to keep oneself from being polluted by the world." James 1:29 (NIV and NAS combined)
In times like these, there are plenty of people that need help. Even in the good times, there are people that genuinely need a hand. And there is always injustice to be found. So much that we can't hope to solve it all by ourselves.
But perhaps it isn't that the world is full of injustice or need because God is unfair. Perhaps it's that they are waiting for us to do the work He gave each of us to do, and reach out to them.
"This is the kind of fast day I'm after: to break the chains of injustice, get rid of exploitation in the workplace, free the oppressed, cancel debts. What I'm interested in seeing you do is: sharing your food with the hungry, inviting the homeless poor into your homes, putting clothes on the shivering ill-clad, being available to your own families.
Do this and the lights will turn on, and your lives will turn around at once. Your righteousness will pave your way. The God of glory will secure your passage. Then when you pray, God will answer. You'll call out for help and I'll say, 'Here I am.'
If you get rid of unfair practices, quit blaming victims, quit gossiping about other people's sins, If you are generous with the hungry and start giving yourselves to the down-and-out, Your lives will begin to glow in the darkness, your shadowed lives will be bathed in sunlight. I will always show you where to go. I'll give you a full life in the emptiest of places— firm muscles, strong bones. You'll be like a well-watered garden, a gurgling spring that never runs dry."
~ Isaiah 58:9-11 (MSG)
God is not unjust. He has put the people in place to do the work that needs to be done to correct injustice and to help the suffering. God is not always "allowing" the suffering. He's waiting for the people He's called to step in and make a change.
What has He asked you to do?
