Medieval canon law barred non-Christians from authority over Christians as blasphemers

Evidence

It would be too absurd for a blasphemer of Christ to be in a position of authority over Christians. … The council declared that converts to Christianity may not keep parts of their old rites, for they “upset by such mixing the decorum of the Christian religion.” Such people must be “completely stopped by the heads of churches from observing their old rite.” — John V. Tolan, Saracens, 1016

Categorization

• XREF: Precursor logic to modern citizenship debates — the idea that Muslim identity disqualifies one from governing Christians recurs in contemporary Europe.