“Among Muslims you have centuries of hatred to overcome; among pagans, centuries of fear.” So declared Cardinal Lavigerie, archbishop of Algiers from 1867 to 1892, and founder of the Pères Blancs, France’s most prolific missionary society in Africa, while describing to his disciples the obstacles they would face in bringing Christianity to Africa through anti-slavery missions (Kittler: 95). His audience well understood the justification for France’s occupation of Algeria, partly staged as a defense against Barbary pirate sieges, whose European captives had once numbered in the tens of thousands. As such, they also understood long histories of French encounters with Islam articulated in the context of race, slavery, redemption, and emancipation. Though this so-called ‘White slavery’ had dwindled to almost nothing by the time of French invasion (especially compared with Black slavery in Algeria and throughout the French Empire), then-salient anti-slavery sentiments furnished French aggression with a chivalrous 'mission libératrice.' This paper will consider the significance of religious reclamation, emancipation, and slave redemption as powerful tropes in this period of French imperial enterprise in Africa, particularly within the language and techniques of the Pères Blancs, and other widely-circulated Church-funded literature issued to advance the cause of Catholic missionising in the Maghreb. The boundaries between ‘European’ and ‘Barbarian,’ between Muslim and Christian, and between ‘White’ and ‘Moor’ were notoriously thin and porous, and Lavigerie and his followers positioned themselves – with great success, in the eyes of their European audiences – at the front guard of this spiritual and temporal battle. Though archival and other sources related to these histories are rich, they remain untapped, as the exploits of the Pères Blancs specifically – and, more broadly, the influence of religious movements on the development of French race-based ideologies of Nation and Empire – have been strangely neglected. Recent scholarship by Patricia Lorcin, Todd Shepard, Julia Clancy-Smith, and others, has addressed this lacuna. Lorcin, for example, has argued compellingly that the nineteenth-century project of racially delineating Mediterranean bodies involved the reinscription of mythologies of Roman-Latin antecedence. This paper represents an effort to deepen this general thesis by emphasizing the role of the Roman-Catholic anti-slavery mandate. Consequently, the wider aim of this paper is to shed light on some origins of perceptions of Muslim-Christian alterity across the French-Algerian transnational space, especially as they inform colonial and postcolonial notions of citizenship and assimilation.