Religious context shapes how inner speech patterns influence auditory externalising bias

Voice hearing has been linked to an externalising bias, i.e. the tendency to misattribute internally generated experiences to external sources. In signal detection terms, this manifests as a more liberal response criterion (greater willingness to report detecting signals). While cultural factors shape voice-hearing experiences, whether religious affiliation influences this perceptual bias remains unclear. We tested whether dialogic and positive inner speech - patterns relevant to prayer and religious cognition - modulate differences in response criterion between Christians (*N* = 27) and non-religious individuals (*N* = 49). Bayesian mixed-effects models found no main effect of religious group, suggesting Christian affiliation alone does not increase externalising bias. However, dialogic inner speech showed a decisive interaction: among Christians, more frequent dialogic inner speech predicted more liberal responding; consistent with religious frameworks that normalise conversation with a divine presence, rich internal dialogue may be more readily attributed to an external source; no such effect was found among non-religious participants. Positive inner speech showed moderate interactions. Among Christians, more frequent positive inner speech predicted more conservative responding, particularly for negative stimuli. Among non-religious participants, more frequent positive inner speech predicted more conservative responding for positive stimuli but trended towards more liberal responding for negative stimuli, consistent with thematic congruence between inner speech content and stimulus valence shaping source discrimination. These findings suggest externalising bias emerges from interactions between inner speech patterns and cultural framework rather than religious affiliation alone.