Medieval Christians classified Islam ambiguously as both heresy and paganism.

Evidence

Peter then gives a rhetorical objection to this line of argument: one could say that the Saracens were pagans (ethnici or pagani) rather than heretics. For did not John define the “many Antichrists” (which, for Peter, means heresiarchs) as those who “went out from us, but they were not of us” (1 John 2:19), in other words as those who had been part of the church and had broken away from it? Peter notes that, like heretics, the followers of Muhammad adopt parts of the Christian faith and reject other parts, while they also follow some rites that seem to Peter “pagan.” Like certain heretics, Peter says, Muhammad “wrote in his impious Koran” that Christ was born of the Virgin Mary, lived without sin, and performed miracles; like the Manicheans, the Saracens deny his death. Like the pagans, on the other hand, they reject baptism, the mass, and the other sacraments. Heretics or pagans, “choose whichever you like” (Contra sectam, §14). — John V. Tolan, Saracens, 852

Categorization

• DEFINE: Shows how the heresy vs. paganism taxonomy blurred when applied to Islam—each label catches part but not all.
• ADDENDUM: Relevant to the immodesty/moral-panic material insofar as it concerns how Christian observers categorized non-Christian belief systems.
• XREF: connects to: Medieval polemicists called Islam a heresy despite its unbaptised status.