This article suggests a rational explanation for extreme voluntary sacrifice in situations in which the state of the world when the decision must be made is observable only by the agent. Such explanation is the cult of martyrs, heroes, and saints. This cult may get out of control and fuel fanaticism, or excessive sacrifice from the standpoint of the sponsoring organization. A survey of the historical evidence of Christian martyrdom strongly suggests that martyrs were driven by the expectation of a cult in this world, not by otherworldly rewards. In particular, it is argued that the evidence of excess martyrdom in both Muslim Spain and the Roman Empire strongly speaks for the cult theory.