This chapter examines the legacy of Iamblichus’ theurgic ideas and their impact on religious and intellectual traditions in the Roman Empire and beyond. It explores how Iamblichus’ Response to Porphyry sought to resignify religious practice, emphasising theurgy as a means of divine communication and spiritual ascent. The chapter highlights the influence of Iamblichus on key figures such as Emperor Julian, who embraced theurgic practices in his attempt to restore traditional polytheism and unify the empire under a renewed religious framework. Julian's reign, though brief, exemplifies the practical application of Iamblichean theurgy in both political and spiritual contexts. The chapter also traces the enduring impact of Iamblichus’ ideas through late antiquity and into the early modern period, where his theurgic principles resurfaced in Renaissance magic, grimoires and esoteric traditions. Despite the eventual dominance of Christianity, Iamblichus’ theurgic framework persisted, shaping Western esotericism and influencing thinkers like Marsilio Ficino and Cornelius Agrippa. The chapter concludes that while Iamblichus’ immediate goal of religious resignification was not fully realised in his lifetime, his ideas left a lasting imprint on the metaphysical and ritual practices of later centuries.