The problem that gives the book its name
Picture the scene: a hospital waiting room, someone asking in a low voice why God lets their mother suffer like that, with all the power he would have to prevent it. The question is old, but C.S. Lewis decided to face it head-on in a small book published in 1940, in the middle of the bombing of London during the war.
The puzzle he builds is simple: if God is good, he would want his creatures to be happy; if he is all-powerful, he could guarantee that without effort. But the world is full of pain, so one of the three seems to be left over. Philosophers have a technical name for this puzzle, theodicy, and the whole book tries to show that you can hold all three points without contradiction.
The author himself gives a warning right at the start: he is writing a rational argument, an exercise in religious apologetics, not a speech of comfort for someone who is suffering right now. A well-built logical explanation does not dry anyone's tears in the moment of pain, and that is not the purpose of the book.
