There is a paradox about tribulation in Christianity. Blessed are the poor, but by “judgement” (i.e., social justice) and alms we are to remove poverty wherever possible. Blessed are we when persecuted, but we may avoid persecution by flying from city to city, and may pray to be spared it, as Our Lord prayed in Gethsemane. But if suffering is good, ought it not to be pursued rather than avoided? I answer that suffering is not good in itself. What is good in any painful experience is, for the sufferer, his submission to the will of God, and, for the spectators, the compassion aroused and the acts of mercy to which it leads. In the fallen and partially redeemed universe we may distinguish (1) the simple good descending from God, (2) the simple evil produced by rebellious creatures, and (3) the exploitation of that evil by God for His redemptive purpose, which produces (4) the complex good to which accepted suffering and repented sin contribute. Now the fact that God can make complex good out of simple evil does not excuse — though by mercy it may save — those who do the simple evil. And this distinction is central. Offences must come, but woe to those by whom they come; sins do cause grace to abound, but we must not make that an excuse for continuing to sin. The crucifixion itself is the best, as well as the worst, of all historical events, but the rôle of Judas remains simply evil. We may apply this first to the problem of other people’s suffering. A merciful man aims at his neighbour’s good and so does “God’s will,” consciously co-operating with “the simple good.” A cruel man oppresses his neighbour, and so does simple evil. But in doing such evil, he is used by God, without his own knowledge or consent, to produce the complex good — so that the first man serves God as a son, and the second as a tool. For you will certainly carry out God’s purpose, however you act, but it makes a difference to you whether you serve like Judas or like John.
— C. S. Lewis, The Problem of Pain (New York: Touchstone, 1996), pp. 98-99.