The Problem of Pain is C.S. Lewis's attempt to tackle the perennial question of suffering in human life. One of the classic objections to Christianity is the following train of thought: God is said to be ultimately powerful (omnipotent), ultimately good, and ultimately loving. He would therefore want what is best for all humans. Suffering, however, exists in the world, and there doesn't seem to be much purpose behind it. If God were both all-good and all-powerful, he would stop this suffering. Therefore, since suffering still persists, God cannot exist.
This is a tough question to answer, and Lewis acknowledges this upfront. In the course of this book, he provides a reasonable solution to the "problem of pain" by explicating God's nature in relation to that of man, demonstrating why the question is loaded by the terms it uses and the assumptions it makes. Even if it seems like Lewis is sometimes using a platitude to avoid giving an actual answer (e.g., his assertions that God's level of understanding is so far above ours that knowledge of what is truly, cosmically within God's will is impossible), atheists must consider what they would deem an adequate response to the question, which seems to presuppose that humans would know what is good for them better than God does, which is an absurd notion.
Many of the protestations concerning the "problem of pain" arise from misconceptions about the nature of human life in relation to God. It is important to understand the overpowering goodness of God's love; his ultimate goal isn't to make humans happy and comfortable. This superficial definition of love trivializes it; what sort of Father, when seeing his children comfortably playing around with a sandcastle on the beach, doesn't drag them away, despite kicks and screams, to show them the real castle he has built specifically for them? God's love is essentially transformative, not passive, and he values our souls more than our earthly comfort. It is also important to realize that, within the Christian paradigm, man is not the center of creation. Most modern worldviews, following the humanist revolution, place man squarely in the center of the universe, but this is clearly not the case when one considers the glory and majesty of God, beside whom all men look tiny and powerless?
By sinning against God, man has employed his free will to rebel against his Creator, bring disharmony and pain into the world. In order to achieve salvation, man must kill his egocentrism and wholly submit himself to God, a process that could never be completely painless. Earthly pain is just a symptom of the real problem: sin, which engenders death. The only way to achieve sanctification is by the painful cleansing of one's soul, a process that is mirrored by the pain and suffering in the surrounding world. This process is perfectly illustrated in Lewis's novel The Voyage of the Dawn Treader, in which Eustace has his selfishness scourged away by the purifying claws of the Lion.
Some might find Lewis's arguments to be too speculative, providing too few concrete answers. This response, however, misses the point; Lewis is not trying to prove Christianity. He is merely demonstrating why the "problem of pain" does not preclude the truth of Christianity, as many claim it does. With that as the standard by which this book should be judged, it comes to light as a resounding success.
