Drawing together scholarship on the late antique and medieval holy man, and modern theoretical work on affect and identity, this article seeks to analyze one method by which group identities in the Mediterranean region broadly, and in Italy specifically, have been defined trans-historically through rhetorical emphasis on the “invasion” of foreignized bodies. The discussion first focuses on late antique Near Eastern Passio texts commemorating Christians who faced persecution under Muslim Saracens, before then shifting to tenth- and eleventh-century southern Italy and Sicily, and to the corpus of Italo-Greek Vitae in which holy individuals regularly encountered the Saracen as a dangerous invader. Such discourses of opposition obscured the inter-reliance between populations, and reduced relations to inherited, primordial struggles, simultaneously shifting attention away from the heterogeneity of non-Muslim resident populations. A similar approach is pursued in modern Italian discourse on migrants, where a selective rhetoric of “invasion” forefront the risks posed by migrants in ways that create a sense of unity in an otherwise-fragmented nation. Urging academic dialogue that incorporates the pre-modern and modern, this article examines the construction of oppositional identity and explores how such narratives reveal collective fears amongst populations threatened by the destabilization of pre-established hierarchies.