Muhammad Abduh claimed in his book "Al-Idtihad fi Al-Nasraniyya wa Al-Islam" that no one had exclusive religious authority in the Islamic world. He argued that the Caliph did not represent religious authority, because he was not infallible nor was the Caliph the person whom the revelation was given to; therefore, according to Abduh, the Caliph and other Muslims are equal. ʿAbduh argued that the Caliph should have the respect of the ummah but not rule it; the unity of the umma is a moral unity which does not prevent its division into national states.