Christian apologists blamed sexual sin, not heresy, for the conquests

Evidence

Yet, far from being a sign that God has abandoned Christians or that he prefers the Ishmaelites, the invasions are a just, even mild, punishment for the sexual sins of Christians. The only other mention of such sexual deviance in the Apocalypse of Pseudo-Methodius is during the second millennium, when “the women were openly running after the men and, like mares in a wild herd, the women, and the men too, had gone mad in an excess of fornication.” The punishment then was the flood; in comparison, seventh-century Christians suffering under the yoke of the Ishmaelites could feel that they were getting off with a light sentence. — John V. Tolan, Saracens, 320 (#corroborates, via linked claim)

When, in 634, the caliph ‘Umar entered Jerusalem as a conqueror, clad in a dirty camel-hair garment, it was a sweet victory for Muslims, a victory of the pious and humble, given by God’s grace. It looked quite different, of course, to Sophronios, patriarch of Jerusalem, who proclaimed: “Verily, this is the abomination of desolation standing in a holy place, as has been spoken through the prophet Daniel.” Muslim victories were punishments of Christians’ sins but in no way reflected God’s approval of Islam. — John V. Tolan, Saracens, 67 (#complicates, via linked claim)

Muhammad, always moved by religious considerations, shocked Christians for this very reason, which made him always appear hypocritical. It was less that wrong practices gave scandal, than that their justification by religion did so. — Norman Daniel, Islam and the West, 571 (#complicates, via linked claim)

Categorization

  • XREF: connects to: Christian writers blamed same conquest on opposing denominational sins; Christians interpreted Muslim conquests as punishment for sin, not divine approval of Islam — John V. Tolan, Saracens, 67; Christian apocalyptic authors read Muslim conquest as deserved punishment for Christian sexual sin — John V. Tolan, Saracens, 320 (+16 more)

Broader Connections