Often we like to give one overarching reason or plausible reason for why God allows evil/suffering, which is known as a ‘theodicy’. However, I think that there are some problems with just trying to give just one plausible reason or reason for why God allows suffering in our world.
One of the problems is that a single theodicy taken on its own can be very weak. Take for example, the soul-building theodicy. The soul-building theodicy says that God allows suffering so that we can build character and learn things through suffering. One of the problems with this theodicy is that it doesn’t account for the suffering of animals. Likewise, the suffering of animals is exactly what you’d expect whether or not there was a God, so in this sense this particular theodicy seems a bit contrived. To illustrate the point, imagine that an all-evil creator who is also omnipotent, and let’s call this being evil-god. With evil-god we can flip the character building theodicy around and call it soul-destruction or character destruction. We could say that evil-god allows some happiness in the world because that’s the price he has to pay in order to allow humans to build immoral character. Building vices of jealousy and rage are the second ordered sufferings that evil-god wants to achieve, so that’s why evil-god allows suffering. If this reverse theodicy won’t work for an evil-god, than why on earth would a character building theodicy work for God?
Notice that we can also do reverse-theodicies or “theodicy flipping” for a number of other theodicies as well. Take for example, free will. Evil-god allows free will because when humans choose moral evils, it is that much worse than if there were no moral evils to choose. We all know that this is a terrible and contrived reason for why evil-god would allow evil. But if it’s a terrible reason for evil-god, why would it then be a good reason for God? Not to mention, free will doesn’t plausibly explain cancer, animal suffering, and the stubbing of the toe. Someone could say that natural suffering is the result of Adam and the Fall. The problem with this is that most people don’t take seriously the notion that we are somehow responsible and justifiably punishable for the sins of another person. We are however responsible for what we ourselves do and have done that are morally wrong. Another problem is whether or not someone needs to first show that the Adam story (or something like it) is plausibly true or that is has actually happened, before they run the Adamic theodicy. The same would go if someone appeal to Satan and his demons for the existence of natural evils. Natural evils are things like aids, hurricanes, tornadoes, etc.
Another theodicy someone can run is to say that, “evil is the absence or privation of good”. First of all, if the person doesn’t expound on that claim, then it is question-begging because they’ve given us no reason to think that it’s true. Secondly, we can run a reverse-theodicy with evil-god. We can just as easily assert that, “goodness is the absence of evil or the privation thereof”. Even if evil isn’t a thing in itself, the burden is still on the theist to explain why God nevertheless still allows it. So even if the theodicy is a reasonable one in explaining what “evil” is or is not, it still doesn’t cover a lot of other questions related to the Problem of Evil.
Yet another theodicy for someone to argue is that God allows suffering because, “This is the best of all possible worlds.” First of all, is the notion of best of all possible worlds even a coherent notion? It seems I can always imagine a world where one more person or one more house exists. Putting that aside, it’s not obvious that this is the best that God can do. Do we really want to say that this world is a better state of affairs than that of Heaven? Likely, no. Furthermore, we can once again flip this theodicy for evil-god. We can say that evil-god allows goodness because this is the worst of all possible worlds. But is this really the worst of all possible worlds? If not, then why is this theodicy any better when flipped back and applied back to God?
Moving on, another theodicy is the “contrast” theodicy. This theodicy says that we need evil in order to understand that good. The problems with this theodicy is that it doesn’t explain why babies suffer and animals suffer. It can also be flipped and be asserted that goodness exists in order for us to understand suffering and evil that much more. Not many people take this reverse-theodicy seriously. But if you don’t take the reverse theodicy seriously, then it seems you shouldn’t take the original theodicy seriously.
One could argue that God allows suffering but not to worry because one day it will be worth it because of Heaven. There are various problems with this line of reasoning. Even if there is a Heaven, the question is still why God allows evil in the here and now? Another problem is that we can flip this theodicy for evil-god. Evil-god allows happiness but don’t worry because one day evil-god will torture everyone in the afterlife for all eternity. It might be objected why evil-god doesn’t just send everyone to hell right now. But we could just as easily question why God doesn’t allow everyone into Heaven right now. In fact, the vast majority of Christians and Christian tradition believe in Hell, so it wont be all laughs and fun for everyone in the end.
Finally, one can argue that God has reasons for allowing suffering, we just don’t know what they are. The idea is that God works in mysterious ways and that we should show a little humility and not assume that we know that mind of God. But this move works just as well for evil-God. Let’s show a little humility and not assume that evil-God doesn’t have reasons for allowing goodness and happiness in the world. But most of us recognize that this won’t work with evil-god. If this is so, then it seems it won’t wash as a move for God either. Also, the theodicy seems somewhat ad hoc. It seems to come in and try to save the day so that we can’t falsify theism. Are we to really expect that an Omnibenevolent being wouldn’t tell us His reasons for allowing evil? It seems that we would expect Him to do so.
As we can see, each individual theodicy or defense taken on its own, is seen to be rather weak. The best move is to somehow make a collection of theodicies and defenses. In other words, don’t assume that God has only one reason for allowing evil. Also, don’t assume there’s just one answer or argument in dealing with the problem of suffering. Lastly, the evil-god challenge has to be answered. It probably won’t do any good in denying that the cases of evil-God are symmetrical to the cases of God. They certainly do seem to be similar. Nor will it do any good to argue that evil-God is an impossibility. Maybe evil-God is conceptually impossible. However, just because things are conceptually impossible, doesn’t mean we can’t also rule out such things on empirical grounds. Not to mention, if evil-God is conceptually impossible, then the theist must explain why God isn’t conceptually impossible as well.