Shirk Of Ahl-ul-Kitab After Itmam-e-Hujjat And The Definition Of Ahl-ul-Kitab
Quran calls each group with the name they call themselves. So much so, it calls the hypocrites believers, beasue they called themselves believers. Since the people of book did not confess that they were polytheists, they are not called polytheists despite telling thier belief to be polytheistic.