“Why is he killing him?” This is what my four-year-old son asked me recently, with alarm. We were reading a children's version of the Bible. We had come to the story of Abraham and Isaac. Abraham is told by God to sacrifice his son Isaac, whom he loves. He starts to obey, and it is only when he is right on the verge of filicide that God changes his mind and calls it off. I had pondered the grim tale many times, and read the thoughts of various theologians and some horrified atheists. I had been fascinated by the nineteenth-century Danish thinker Søren Kierkegaard's line: the story should remind us that God is beyond human morality and rationality, that we have to trust him. It is the model for all faith. As I'll relate later on, this interpretation was an important influence on my own experience of Christian faith.

The shock of the story had become largely theoretical over the years, but now, reading it with my little boy, it felt fresh again. He was glancing up at me, demanding an explanation. “Why is he killing him?” I mumbled something about God playing a sort of trick on Abraham, but everything being all right in the end. If he were older I might have tried some Kierkegaard on him, or I might have taken an anthropological approach, and explained that ancient religion was tied up with human sacrifice, and that this story seems to mark a rejection of that. You can, to some extent, explain this story away.