Each religion saw the other as a corruption of its own truth.

Evidence

Just as Muslims believed that the doctrines held by Christians were a corruption of those teachings of Islam which God had revealed to them through Jesus, so Christians could only see Islam as a corruption of Christian truth. — Norman Daniel, Islam and the West, 1039

Categorization

• CANDY: The mirror-image ‘we have the original, they have the corruption’ claim is a clean way both faiths positioned each other.
• corroborated: 2 independent passages support this claim — Norman Daniel, Islam and the West, 1039
• XREF: connects to: The belief in eternal truth drove systematic misreading of Islam. — John V. Tolan, Saracens, 162; Medieval polemicists claimed Islam mixed truths with lies to deceive believers — Norman Daniel, Islam and the West, 904; Identical source material can yield opposite religious impressions (+5 more)

Broader Connections

• Medieval polemicists claimed Islam mixed truths with lies to deceive believers #exemplifies (0.90) — Norman Daniel, Islam and the West, 904
• The belief in eternal truth drove systematic misreading of Islam. #expands (0.85) — John V. Tolan, Saracens, 162
• Medieval Christian-Muslim disputation mostly argued from premises neither side shared #expands (0.85)
• Medieval polemicists used Jewish and Islamic scriptures to refute each other reciprocally #exemplifies (0.85) — Norman Daniel, Islam and the West, 311
• Identical source material can yield opposite religious impressions #expands (0.80)
• Polemics could condemn a rival religion using only its own scriptures #exemplifies (0.80)
• War and mutual contempt prevented either side from understanding the other’s worship #expands (0.80) — Norman Daniel, Islam and the West, 1140
• Shared religious premises make inter-Abrahamic conflicts more virulent than cross-civilizational ones #expands (0.75) — Bernard Lewis, From Babel to Dragomans, 1036