The present thesis endeavors to identify the context out of which the conceptual category of heresy initially emerged within early Christianity. As such, it will not focus on any single heresy or heresiological issue, but rather on the emergence of the notion of heresy itself. The context proposed from which the Christian idea of heresy first emerged is not the institutionalization of orthodoxy within the second-century church, but rather, the dynamics of internal social conflict, which is visible in situations of internal deviance within first century Christianity and in at least one strand of the sectarianism of Second Temple Judaism. In Part I, which is a single chapter (two), I appeal to the social sciences to help articulate a social understanding of the concept of heresy, not in an effort to replace the ecclesiastical understanding, which holds heresy to be a belief or teaching that stands in opposition to or deviates from an orthodox norm/doctrine and which dominates scholarly perception on the topic, but as a complement to it. The aim of the chapter is to identify a set of characteristics that mark heresy as a unique social phenomenon. In Part II, I turn to Galatians (chapter three) and parts of Revelation 2-3 (chapter four), as test cases for the viability of locating the phenomenological characteristics noted in chapter two within these two first-century contexts of internal social conflict. After surveying the settings of conflict and the given author's responses to them, I conclude that though heresy (in the ecclesiastical sense) is not demarcated in these contexts, they are a likely context out of which the early Christian conceptual category of heresy initially emerged. Part Ill reflects an effort to see whether there may be earlier settings of internal social conflict that are analogous to these first-century contexts. Based on the argument that the exclusiveness inherent to these first-century situations of internal conflict, as well as the notion of heresy, requires a monotheistic religious framework, I turn solely to Second Temple Judaism. Relying upon a phenomenological characterization of religious sects, I (in chapter five) highlight the emerging sectarian markings evident in groups around the beginning of the second Jewish commonwealth. Chapter six, then, reflects an attempt to gauge the extremes of sectarian commitments and expression in late Second Temple Judaism by noting the sectarian features of groups behind the Habakkuk Pesher and the Psalms of Solomon. Ultimately, I conclude that these two settings of sectarian conflict bear a phenomenological resemblance to the first-century Christian situations of internal social conflict previously surveyed. Part IV, which is a single chapter (seven), reflects an effort to track when and how the early Christian notion of heresy emerged from these settings of internal social conflict, primarily through a study of the New Testament evidence of [Greek characters];. As the term moves from possessing a neutral to a pejorative to a defamatory meaning, I appeal to linguistic theory, namely semantics and sociolinguistics, in an effort to (1) characterize the type of shift in meaning that occurred in [Greek characters]; and (2) begin to locate any forces or factors that may have been influential in this linguistic transformation. Ultimately, I combine this analysis of [Greek characters]; with the previous work on the dynamic of internal social conflict in the first century and the late Second Temple period to construct a diachronic presentation of how the concept of heresy initially came into early Christian thought and writing. Chapter eight brings the thesis to a close by briefly revisiting the main conclusions of the study and identifying the primary contributions that it makes to various areas of Christian Origins research.