When asked "If there is an omnipotent and good God, why is there suffering in the world?", the most common response Christians give is something along the lines of "Suffering is a necessary consequence of free will, and it is more important to God to allow free will than to eliminate suffering. All the suffering is ultimately caused by free will.".
I think one of the most serious problems with that response is that suffering predates free will by hundreds of millions of years. Which all beings have free will? I don't think anybody would seriously argue that non-human animals have free will, in the sense that they should be held responsible for their actions. And human beings have existed for, let's say, two million years. But which all animals are capable of suffering, at least feeling physical pain? It's hard to tell, the general consensus seems to be that it is birds and mammals and perhaps octopuses. The latest common ancestors of birds and mammals existed 300 million years ago. Now, many people think that the ability to feel pain has evolved separately in birds and mammals, so that would push the number of years suffering has existed to lower, but we are still talking about hundreds of millions of years. So, for hundreds of millions of years, there was suffering in the world, but there was no free will. How do the proponents of the "free will" theodicy explain that?