The study assesses the religion-delinquency literature by using a methodological approach to reviewing a body of literature that is new to social sciences: the systematic review (SR). This SR revealed that the literature is not disparate or contradictory, as previous studies have suggested. Religious measures are generally inversely related to deviance; this is especially true among the most rigorous studies. A commitment to religious values and beliefs can have both an immediate and a long-term impact on youths’ behavior. In this regard, religion could be treated as both a proximate cause of delinquency and a time-stable individual trait that influences an individual’s inclination toward antisocial behavior. As criminologists continue to examine the neglected topic of religion (what has been referred to as the forgotten factor), this article is a warning that measurement issues around a complex topic such as religion, or even spirituality or forgiveness, is of paramount concern. Tables, appendixes, note, references