Paul C. H. Lim offers an insightful examination of the polemical debates about the doctrine of the Trinity in seventeenth-century England, showing that this philosophical and theological re-configuration significantly impacted the politics of religion in the early modern period. Through analysis of these heated polemics, Lim shows how Trinitarian God-Talk became untenable in many ecclesiastical and philosophical circles, which led to the emergence of Unitarianism. He also demonstrates that those who continued to embrace Trinitarian doctrine articulated their piety and theological perspectives in an increasingly secularized culture of discourse. Drawing on both unexplored manuscripts and well-known treatises of Continental and English provenance, he unearths the complex layers of the polemic: from biblical exegesis to reception history of patristic authorities, from popular religious radicalism during the Civil War to Puritan spirituality, from Continental Socinians to English anti-trinitarians who avowed their relative independent theological identity, from the notion of the Platonic captivity of primitive Christianity to that of Plato as Moses Atticus. Among this book's surprising conclusions are the findings that Anti-Trinitarian sentiment arose from a Puritan ambience, in which Biblical literalism overcame rationalistic presuppositions, and that theology and philosophy were not as unconnected during this period as previously thought. Mystery Unveiled will fill a significant lacuna in early modern English intellectual history.