Consider these words of Paul from his second letter to the Corinthians:
We do not want you to be unaware, brothers and sisters, of the affliction we experienced in Asia; for we were so utterly, unbearably crushed that we despaired of life itself. Indeed, we felt that we had received the sentence of death so that we would not rely on ourselves but on God who raises from the dead. He who rescued us from so deadly a peril will continue to rescue us; on him we have set our hope that he will rescue us again, as you also join in helping us by your prayers, so that many will give thanks on our behalf for the blessing granted us through the prayers of many (2 Cor 1.8-11).
Why do people suffer so badly in the world? If ever there were a question which led a person to disbelieve in God, it would be this one. It's a question for which there are no easy answers, and certainly there are no answers which apply equally well in every case. Sometimes we have to sit back and be silent in the face of mysterious phenomena. Such a thing is certainly not easy in our scientific age, in which we are convinced that we can figure out the answer to every question, the corollary of this being that if we can't find a reason for some thing, there must not be one.
Yet I think there is at least this response which can be given: suffering occurs to reorient us towards God. And inevitably this is what takes place, whether this reorientation is manifested through prayer for deliverance and faith, as in the case of Paul and his missionary crew, or else in the case of angry protest as in many of the psalms. If the bible were to give a single answer to the question of the reason for suffering, it would be this one: to turn our minds and our hearts away from the quotidian and the sensual, and to think of and speak to God.
The ancient patristic authors such as Athanasius wrote that Adam and Eve would have continued on in immortality, if only they had not turned their minds from the contemplation of God. Their life was supposed to be a God-centered, God-saturated one. Indeed, this what our lives will be like, since the bible tells us there will be a time when God will be all in all (1 Cor 15.28). Consider Jesus Christ himself, our model, whose life was eminently a God-centered life: he spent his nights praying and crying out prayers and supplications, with loud cries and tears, to the one who was able to save him from death (Heb 5.7); and he spent his days serving others and teaching about the kingdom of God to those who were in need. This is the sort of life God intends us to live, and suffering is a way of nudging us in that direction.
Suffering awakens within us that sense that all is not right, that things are not as they should be. This awareness, furthermore, obviously directs our attention to the one who ultimately ought to be taking care that things go right -- to God himself. But then what?
Once we have been so oriented towards God by the suffering we see and experience, the bible calls us to do one more thing: to trust; to repent and believe the good news that God is actually king (cf. Mark 1.15), that his will is actually being accomplished in the things that are taking place, though it may seem impossible and wild to our own minds. Trust in God and depend on him with everything; trust that he can raise even the dead, so that even death is a conquerable evil. Trust that he will deliver you from every evil, even if the way in which this deliverance is realized may not be what you desire or anticipate.