Musnid al-Hind, Imam al-Akbar Hazrat Shah Waliullah Muhaddith Dehlavi (RA) has stated that for the completion of the belief in Tawhid, it is necessary to believe in four levels of Tawhid. If there remains even an atom's weight of deficiency in any level of Tawhid, a person can never be called a monotheist (Muwahhid). Those four levels are: (1) Tawhid al-Dhat (Monotheism of Essence): That is, to believe that the Necessary Being (Wajib al-Wujud) who has always existed and will exist forever is solely the Essence of Allah Almighty; this attribute is absolutely not found in anyone other than Allah Almighty. (2) Tawhid al-Khalq (Monotheism of Creation): That is, to accept that the Creator of the heavens and the earth, the Throne (Arsh), the Chair (Kursi), and all creation is solely Allah Blessed and Exalted, and He has no partner or associate in the attribute of creation. This is also called Tawhid (al-Rububiyah). (3) Tawhid al-Tadbeer (Monotheism of Governance): That is, to firmly believe that whatever has happened, is happening, or will happen in the universe, the only One running it all is Allah Almighty. No one else has any involvement whatsoever in running this system, and Allah Almighty is the sole Master of His own will; no one can stop His decision. (4) Tawhid al-Uluhiyah (Monotheism of Worship): That is, to hold the belief that only the Essence of Allah is worthy of worship, and it is never permissible to make anyone other than Allah a deity. For Tawhid al-Tadbeer, Tawhid al-Uluhiyah is necessary; meaning, the One who runs the universe is the only One worthy of worship. (Hujjatullah al-Balighah, along with Rahmatullah al-Wasi'ah 1/590) Among the above-mentioned levels of Tawhid, the first two levels, namely Tawhid al-Dhat and Tawhid al-Khalq, were generally acceptable even to many polytheists (mushrikeen), and even today, the state of most polytheists is that they accept only one Creator (whom they call "Ishwar" or "Bhagwan" etc. in their own language). However, they were neither ready in the past nor are they ready today to accept the third and fourth levels of Tawhid. Although, without believing in them, no concept of faith (Iman) can be made. (Sharh al-Aqidah al-Tahawiyyah by Imam Ibn Abi al-Izz al-Dimashqi 21) (Benefited from Rahman ke Khas Bande / p. 196)