Christians insisted Islam differed from Christianity to keep boundaries clear.

Evidence

These Byzantine church leaders need to affirm the religious alterity of Islam in order to keep the boundaries clear between religious truth and error: better to associate Islam with pagan idolatry than to suggest that it venerates the eternal God. — John V. Tolan, Saracens, 684

Categorization

• XREF: Directly grounds the vault’s Islam-West opposition claims: identity boundary-maintenance, not just ignorance, drives polemic
• ADDENDUM: Supports the framing of religious identity as boundary-marking over theological accuracy, echoing the immodesty-panics article’s logic of identity signaling