Examines the grounds upon which theistic belief might be justified as a reasonable theory. The Judaeo-Christian religious belief-system is used for purposes of illustration. It is argued that this system can be construed as one in which theoretical entities identified as gods are posited in order to account for unique events which appear to be otherwise inexplicable. Recent work in philosophy dealing with the structure of theories positing theoretical entities is surveyed in developing this position. 'God' is viewed as acquiring its meaning by the role the supposed referent plays in relation to events in human experience.