This chapter provides a comprehensive exploration of polemical literature in early Islam, focusing particularly on the dynamic landscape during the Umayyad era. It illuminates the emergence of various sects and doctrinal disputes that significantly influenced the course of Islamic history. While existing scholarly analyses often concentrate on polemics from the third century onward, this study fills a crucial gap by delving into the literature of the first two centuries, offering a nuanced understanding of early Islamic thought. The investigation encompasses key Sunni theological works such as Laalaka’i’s Sharh As Sunnah, ājurry’s Ash Shariah, and historical texts like Ibn ʿAsakir’s Tarikh Dimashq. Additionally, Shi’i literature including Al Kaafi of Al Kulayni is scrutinized. By examining these texts, the chapter seeks to uncover the underlying objectives and intentions of polemical discourse, particularly from a Sunni standpoint. In doing so, the chapter aims to elucidate whether Sunni scholars intended to dissuade the adoption of prevailing ideologies deemed incompatible with Islam, while concurrently highlighting the doctrinal principles advocated by the Prophet Muhammad’s companions. Through this exploration, it becomes evident that the multifaceted nature of religious discourse during this period had a profound and lasting impact on Islamic philosophical theology, shaping its development and trajectory.