De fide catholica

Alan of Lille's De fide catholica contra haereticos sui temporis is a four-book late-twelfth-century exercise in Christian polemic. Written in the scholastic world of Paris and southern France, it organizes arguments against the religious positions Alan associated with Cathars, Waldensians, Jews, and Muslims, using Scripture, patristic authorities, and dialectical reasoning to articulate Catholic doctrine. The work is valuable both as a theological synthesis and as evidence for how learned Latin writers classified and contested religious difference; modern historians caution that its descriptions are polemical constructions, not transparent reports of communities. Schola presents the Latin text and an English translation.