Why does God allow suffering?

Secular

The amount and kind of suffering in the world is hard to fit with a God who is both all-good and all-powerful. This is most true of animals that suffer unseen, where no one can learn from it. It makes more sense, they say, if there is no such God.

The case for it

The philosopher William Rowe argued that a good and all-powerful God would stop any suffering He could. The only exception is suffering He could not stop without losing a greater good, or allowing an equal or worse evil. His example is an imagined fawn, burned in a forest fire started by lightning, lying in agony for days. We see no good this serves, so Rowe held that it is reasonable to believe there is none. He concluded that it is reasonable to believe the God of traditional belief does not exist.

Where it falls short

Grant that we see no reason. That shows little, since we should not expect to see every reason of One who knows all. Rowe himself granted that a believer with good reasons to believe in God (﷾) may reasonably reject his starting point.