Why give money to beggars? Why make sacrifices to help others? The current volume targets such questions with the tools of neoclassical and behavioural economics, philosophy, and sociology of religion. Both religion and economics are analyzed as social institutions that support human intra-group cooperation. Even if individuals are rational maximizers of personal utility, they yet must take into account the reciprocal nature of human relationships. It is better to be part of a cooperative group and make some personal sacrifices because, in the end, everybody benefits from this. Sometimes the metaphor of an invisible hand is used to describe the fact that economic exchange seems to