Anti-Muslim polemic served to police Christian doctrinal boundaries against internal rivals

Evidence

Christians feared Muslims both as a radically other religious competitor and a despoiled fraction of Christians. Deprecating Muslims often served efforts to police the doctrinal boundary circumscribing “true Christianity,” as seen in Roger Williams’s answer to Quaker founder George Fox in G. Fox Digg’d out of His Burrows (1676). — Carl W. Ernst, Islamophobia in America_ The Anatomy of…, 157

Categorization

• XREF: Directly parallels the reader’s guiding question about projection/displacement — Muslim caricature as a screen for policing fellow Christians (Quakers, Mormons, Catholics), the very ‘close rival’ logic of heresy.
• SEED: Angle: depictions of the ‘other’ religion double as tools for policing the in-group’s own orthodoxy — who is really being disciplined when we denounce the enemy religion?