European slavery was already elaborate before Islam and rejected Muslim slave ideals as heretical

Evidence

That Christendom failed to be impressed by Islamic law and customs on this matter is hardly surprising since the traditions of European slavery were already quite ancient and quite elaborately rationalized by the time of the appearance of Islam in the seventh century. Moreover, it was highly improbable that the Christian establishment of the medieval era would countenance the adaptation of customs from what they considered the ultimate Christian heresy—Islam, many believed, was based on sexual license and forced conversion; and finally, Western xenophobia—so critical to the character of European identity and so fundamental to Christian slave systems—expressed a revulsion toward Muslim ideals. — Cedric J. Robinson, Black Marxism_ The Making of the Black…, 500

Categorization

• XREF: This names Western xenophobia as ‘critical to the character of European identity’ — an early Robinson claim about race as foundational to Europe, which the reader’s arc needs for the tradition’s origins.
• DEEPTHINKING: Robinson’s compression here — European slavery antedates Islam, rejects Islamic slave law for theological-political reasons, and ties xenophobia to the core of European identity — is a dense causal knot that reframes the entire race question.