Maybe the answer to the following question "If there is a God why is there so much suffering in the world?" is in the title of my post, but I'll dig deeper in this anyway !
The first thing I noticed in that contest is the comment from 
From what I read, those of us who believe in God are not invited to give our opinion.
But, I was glad to see 
Of course before answering the question, I think that I have to show my position about God. You may read about it here : My relation with God !. Or I'll write the main idea about that. For me, God is the power that created the world and the same power controls all the events happening during the time. So, in my opinion every move we make, every little thing happening in the world is all the will of that power. And it's impossible for anyone to change it, or to do it otherwise !
Following my thoughts, we can say, that I accept all the suffering happening in the world. But, that's not true. Most of us don't like to see any suffering, because we are all born as good people. I don't think that any little child can do a bad thing or let others suffer. Kids are saint. So, the human being can absorb the good and the bad during his/her life. And mostly the effect of the surrounding and the lifestyle may change the person for better or worse. Even beliefs are coming from the information he/she consumed during life. And if that's all pushed by the power that we call God, so God plays the main role in the suffering of any alive creature.
That doesn't mean that God is good or bad. Because he doesn't have to be like that, he should be objective. And everything happening should have a meaning, or a reason.
For example, looking at the animal world. Can we say that some animals are suffering because God doesn't exist ? Or maybe the main reason of the existence is the procreation ? That's why the strong animal has to eat the weaker. And even the weak animal eats plants and in this case we can say that plants are also suffering. But, in the end we come with a conclusion that plants aren't suffering, but who can prove that. Anyway, as you see to have a continuation of the life, someone, or something has to suffer.
Talking about people. Aren't we all suffering by getting older, weaker and in the end dying ? Aren't we suffering when we lose our close people ? Aren't we suffering when we have to waste so much time in sleeping, working and eating, instead of taking care about more important things ? Aren't we suffering from the unfair distribution of resources ? Not only the material resources, but sometime worse health, fewer opportunities ... etc. I always write that we aren't trees, we can move, we can change, so if we do something about it, we may always find solutions and do what we can do to not suffer. We shouldn't blame God for not helping us. Because in fact, we can help ourselves and God is giving us the choice. And maybe even the choice is already destined by him, but that's all to give the example to the next generations. The example that to not suffer, you have to make the change.
Maybe you think now : what's the reason if everything is predetermined ?
I would say that everything is predetermined to support the reproduction. And maybe even the improvement. Because we don't have to live an eternal life to affect this spiral of life. Everyone and every living creature and even the thing have its role. Its reason to exist. Once that accomplish the mission, there is no reason to exist anymore. Maybe that sounds tough, but it's the reality. So, if a creature is still alive, if something still exists, that means the mission is not done yet. That's why everyone should think about that mission to not give up on life. That's how things work and that should be just accepted.
The same about suffering. The power that created all this world and all the living creature in it, knows better what needs to improve and flourish and what should get the attitude it's getting.