FROM RICHARD SWINBURNE, EMERITUS NOLLOTH PROFESSOR OF THE PHILOSOPHY OF THE CHRISTIAN RELIGION AT THE UNIVERSITY OF OXFORD: The existence of pain and suffering and other forms of evil is the strongest argument against the existence of God. God is supposed to be omnipotent and perfectly good. But, being omnipotent, he could remove all the evil from the world; and being perfectly good, he would surely seek to do so. So, the argument concludes, there is no God.
However, God's omnipotence is only supposed to be the power to do anything that is logically possible to do—so, for example, he cannot make me exist and not exist at the same time; he cannot do the logically impossible because it makes no sense to suppose he could. And a perfectly good being may well allow evil to occur if that is the only way this being could promote a great good. So God may well allow evil to occur if, without allowing the evil to occur, it is not logically possible for him to promote some great good.
Much of the evil in the world is caused by the actions of human beings, who cause it deliberately or allow it to occur through negligence. Given that humans have free will, it is not logically possible for God to allow humans to choose whether or not to cause or allow evil and yet ensure that they always choose not to. And it is a great good for human beings to be responsible for each other. You can only really be responsible for someone if it is within your power to give that person either a good life or a bad life; if God had given you only the power to determine what kind of good life came to somebody else, it wouldn't really matter what you did. But isn't it hard on the other person, who is thus dependent on you?
Not necessarily. Suffering provides a great opportunity in how one chooses to cope with it—either by feeling sorry for oneself or by showing patience and courage. Each good choice we make makes it easier to make a good choice the next time, and each bad choice makes it easier to make a bad choice next time. Therefore, our actions are not merely good or bad in virtue of their immediate effects on others but also in virtue of their effects on our own character. Obviously, not all evils are caused or allowed by humans; there are the evils caused by accidents and diseases that are currently unpreventable by humans. Yet without these, we could argue, humans would have relatively little opportunity for character formation.
So, the religious defense against the problem of evil is that evil provides great opportunities for free and responsible choice and character formation that would otherwise not be available to us. Of course, God would be mad to cause endless evils in order to give us endless such opportunities. And if there is a God, that’s not what happens. Only for the limited period of our earthly life are there such opportunities, but with them we can form a character suitable for another life.

Richard Swinburne appears with Quentin Smith, Michael Tooley, Alvin Plantinga, and Peter van Inwagen in "Does Evil Disprove God?" the 21st episode in the Closer to Truth: Cosmos, Consciousness, God TV series, hosted and created by Robert Lawrence Kuhn. The series airs Thursdays on the PBS HD network and many other PBS stations. Every Friday, participants will share their views on the previous day's episode.