The flood that God used to destroy the sinful race of man on Earth in Genesis 6:17 crystallises in its terrifying, dramatic simplicity the universally recognised concept of payback. For millennia human civilisation has relied on such beliefs to create a moral order that threatens divine punishment on people who commit crimes, while promising rewards – abstract or material – for those who do good. Today, while secularism and unbelief are at an all-time high, this almost superstitious willingness to believe in karma persists. Why?