A common theodicy attempts to explain the problem of evil by claiming that our ability to choose God can only be truly free if we are able to do evil also. Suffering is a necessary consequence of free will.
There are several problems with this theodicy, some of which I have discussed before (see my post on the firing range theodicy, for example). But a further problem struck me just recently.
The best decisions are made, I believe, when we are calm, comfortable, unhurried, and in possession of all the necessary facts.
A world full of suffering is not conducive to this ideal decision-making state. We struggle to make wholly rational decisions when we are in pain. We also struggle to make rational decisions when we are grieving someone else’s pain (or death), or when we are worried about our (or others’) possible future suffering (as a poor person in need of food may be).
It would therefore appear to be against God’s interest to allow suffering to occur. Suffering lowers the probability that we will make wholly rational decisions about whether to follow him.