Based on Herbert's (1987) theory of ego identity development and on interviews of hundreds of Israeli religious male adolescents and young adults who were raised and educated in religious society and later left the fold, this article presents a model of development of religious identity. Three levels of religious identity development--healthy, unhealthy, and dangerous--are described. In healthy development, adolescents abandon childish faith, confront and deliberate about their doubts, and consolidate a mature and personal spiritual identity. Unhealthy development, which may occur if doubts are not accepted and dealt with, is seen in four forms: sloganeering, diffuse spiritual identity, moratorium, and emphasis on ritual and behavioral aspects of religion. These, in turn, may lead to dangerous developments: (1) joining a cult or enslaving oneself to a charismatic leader; (2) joining a group of formerly religious peers; (3) group delinquency (theft or vandalism) or group use of alcohol or drugs; (4) alienation and anti religious attitudes; (5) inconsistency or "being religious at heart"; (6) solitary use of alcohol or drugs, possibly leading to addiction. Methods of preventing and correcting unhealthy and dangerous developments are presented and discussed. (Contains 7 footnotes.)