This book examines how faith and happiness intersect. It reflects on why religion and happiness are positively related, and why believers are often shown to be happier than non-believers. The author provides an overview of existing literature on religion and happiness and draws on in-depth empirical research. The chapters touch on questions such as: Which aspects of religion are related to happiness? What factors moderate the relationship between religion and happiness? Under which conditions is the relationship stronger or weaker? The book also investigates whether and how the empirical findings of happiness research are relevant from a theological perspective. It asks why Christians might be skeptical about the relationship between faith and happiness, and whether this perception is rooted in the Bible texts and the church tradition. The author considers the implications of the research for those (believers and non-believers) who live in a society where happiness is often seen as the highest value, and what lessons churches can learn from the results. This book is relevant for a broad audience of theologians, sociologists, psychologists, and more generally, academics who are interested in the relationship between religion and happiness.