This article has three aims, all of them related to the theory and practice of intertextuality. Firstly, the article makes an attempt to reconstruct the Augustinian-Lutheran type of discourse. A number of modern theologians and historians of philosophy have observed that the main currents within Christian theology have their basis in a specific discourse organization of textual utterances. With reference to these observations, the article maps out some dominant features of Augustine’s and Luther’s discoursive practices. The type of discourse thus reconstructed contains grammatical, logical-argumentative, narrative and rhetoric-figurative characteristics, and – as a matter of fact – it manifests a high degree of applicability in the field of literary studies. Secondly, the article applies the reconstructed type of discourse to analyze a masterpiece of Swedish twentieth-century literature, the novel Dykungens dotter (The Marsh King’s Daughter, 1985) by Birgitta Trotzig (1929–2013). In several interviews, Trotzig makes evidently contradictory remarks on Augustine and Luther. She dissociates herself from their anthropology at the same time as she hints that their view of human conditions has made a deep impression on her. The article’s application intends to throw light on this precarious hermeneutic situation. The intense presence of the Augustinian-Lutheran type of discourse in the novel made apparent through the application indicates that an interpretation of Trotzig’s writings by means of Augustinian-Lutheran intertexts is hermeneutically motivated in spite of her own negative declarations. Thirdly, the article makes use of the reconstructed type of discourse in order to examin Gérard Genette’s notion of architextuality. There is a theoretical incongruence in his notion. On an explicit definitory level, architextuality includes all types of discourse and modes of enunciation. On a conteptual level, however, the notion of architextuality is constructed on the pattern of literary genres. The article’s application demonstrates that Genette’s notion requires some corrections to live up to its definitory commitments. The Augustinian-Lutheran architext comes into conflict with some of Genette’s linguisticly construed structuralistic categories and demands a more discoursive and hermeneutic way of thinking.