Even if some ignorant people do believe such a thing—as is reported of certain ignorant Kurds(1) and others like them: one believes that Yazīd was one of the Companions, another that he was one of the prophets(2), while others believe that he was one of the Rightly Guided [and rightly directed] Caliphs(3)—such people are not scholars whose opinions merit citation.
Despite this ignorance, they are still better than the ignorant among the Shia and their heretics, who believe in ʿAlī’s divinity or prophethood, or believe that the inward meaning of the revealed law contradicts(4) its outward meaning. The Ismāʿīlīs(5), the Nusayrīs, and others maintain that fasting, prayer, pilgrimage, and almsgiving cease to be obligatory for their elite, and they deny the resurrection. Indeed, their extremists even deny the Creator. They believe that Muhammad ibn Ismāʿīl was superior to Muhammad ibn ʿAbd Allāh ibn ʿAbd al-Muttalib and that he abrogated the latter’s revealed law. They also believe that their imams—such as the one they call the Mahdī and his descendants, including al-Muʿizz, al-Hākim, and others like them—are infallible imams.
There is therefore no doubt that anyone who believed all the Umayyad and Abbasid caliphs to be infallible would be better than these people in many respects. The Umayyad and Abbasid caliphs were Muslims both outwardly and inwardly, and their sins were of the same kind as those committed by other Muslims; they were not disbelieving hypocrites.
These Bātinīs (esotericists), however, are inwardly greater disbelievers than the Jews and Christians. Thus, anyone who believes them to be infallible is far more ignorant and misguided than someone who believes the Umayyad caliphs to be infallible