The reality of suffering causes many questions about the nature of God. It is known as the "problem of evil" or more specifically "the problem of pain." Often people come to conclude that there is no God because there is evil in the world. However, this is a problem of itself. Let us leave aside the fact that atheists who argue against the existence of God from "the problem of evil" do not themselves acknowledge evil as a reality. This means that we cannot take their premises or even argument seriously. If we acknowledge that there is evil then we acknowledge that there is a moral law. If we acknowledge a moral law than we acknowledge a moral law giver. The existence of evil and the "problem of evil" therefore nails the case closed for God who is the moral law giver. If there is no Moral Law Giver then there is no moral law, and if there is no moral law, then there is no good or evil. Either one acknowledges the premises of the argument or they do not. If they do not, then they cannot use the argument against the Biblical God. This is not a matter of paradox, but of logical incompatibility. One must either consistantly and fully acknowledge the premises as being true or not, for other than that is hypocrisy and deception.
Sickness, Suffering, and Death--from the Orthodox Faith series by Fr. Thomas Hopko
Passages from Saints on suffering
Other quotes from Saints and writers on suffering
Podcast on Suffering from an Orthodox Christian perspective