Spanish Muslims were not visually distinguishable from Christians by appearance alone

Evidence

So it may well have been the case that in the sixteenth century the Muslims of the peninsula did tend to be darker in color than their Christian neighbors (although we cannot assert that with any degree of certainty). But any difference of appearance or complexion that may have been observable over the whole population certainly did not apply to all individuals. And if there were differences of skin pigmentation, they were not so marked that one could tell at a glance to which community a person belonged. (If the Inquisition had been able with confidence to tell from a man’s face what were his religious allegiances, it might have been spared the embarrassing task that had to be undertaken during some of its trials: that of inspecting the prisoner’s foreskin.) — L. P. Harvey, Muslims in Spain, 1500 to 1614, 81

Categorization

• CANDY: The Inquisition’s foreskin inspections as a failed racial test is a darkly absurd, tweetable tidbit.
• SHARE: Send to anyone interested in the history of racial classification tests or the Inquisition.