Christians and Muslims could ally against pagans over shared monotheism.

Evidence

The next question was to decide whether to take on the Buddhists or the Moslems in the first instance. The Nestorians strongly favored an immediate attack on the Moslems; but here again they showed their dialectical simplicity. As William pointed out, the Christians and Moslems agreed on the fundamental points of the nature and existence of one God; so, as against the Buddhists, they would start as allies; but in a dispute with the Moslems the Christians would have no allies at all. — R. W. Southern, Western Views of Islam in the Middle…, 308 (#corroborates, via linked claim)

When it came to debating about the existence of God in front of pagans, it was realised without difficulty that there was community of belief with Islam. William of Rubruck recounted how he had had to point out, ‘the Saracens agree with us in that they say there is one God; they would therefore be on our side against the ¢uims’. — Norman Daniel, Islam and the West, 265 (#exemplifies, via linked claim)

Categorization

  • XREF: connects to: Christians expected Muslims to ally with them in asserting monotheism against Buddhists; Shared monotheism made Christians and Moslems natural allies against Buddhists — R. W. Southern, Western Views of Islam in the Middle…, 308; Christians fantasized Muslims as pagan idolaters to justify crusading violence (+4 more)

Broader Connections