Sacrifice is the cost of religion, paid in many ways, including donations, ascetic self-denial, prayer, fasting, mystical ecstasy, imitative suffering, ritual offerings, and martyrdom. Common religious discourse uses “sacrifice” to describe a wide array of events and actions that exhibit common features, such as reference to transcendence, conditionality of the offering, and an element of self-giving. For Judaism, Christianity, and Islam a guiding example of sacrifice is the Hebrew patriarch Abraham, who was willing to offer his son to God as a burnt offering. Each tradition appropriates the story in different ways, but they all uphold sacrifice as a means of relating to the sacred and as an ideal of human conduct. Most theories of sacrifice locate its function in the formation of social order, but this book focuses on sacrifice as the exchange of concrete natural and human goods for abstract spiritual benefits. As such, sacrifice both signifies a transcendent ideal of individual or communal fulfilment and poses a moral danger of sanctioning the imposition of that ideal on others. In Judaism and Christianity, animal sacrifice is displaced by acts of devotion to God and charity toward others; in Islam, animal sacrifice remains a religious duty during pilgrimage to Mecca but is understood as an expression of gratitude to God and a donation to those in need throughout the Islamic world. Thus, each tradition interprets sacrifice as both religious ideal and moral obligation.