Islam is based on the belief that all existence has a single god (tawhid).[1] Prophet Muhammad(Peace and blessing be upon him)’s greatest struggle was with polytheism (polytheistic belief).[2] The opposite of monotheism can be in two ways: either it is believed that there are many absolute authorities with divine power, or it is believed that there is only one great deity, but that he shares some of his powers with several more deities.
It can be understood from the order and functioning of the universe that both options are impossible, and this is the strongest evidence of Allah’s unity.[3]
The functioning of the universe is in a flawless order, with all its parts interrelated. For example, while the water droplet penetrating the soil nourishes it and provides a source for life, the formation of that water droplet depends on the movement of the entire solar system, and the solar system depends on the well-functioning mechanism of space. This astonishing order reveals that whoever puts the internal organs of a butterfly in their proper place, can be none other than He who arranges the layers of the atmosphere together.
Only a single deity can govern such an ongoing order.[4] Let alone a country, a city, a school, or a hospital, that is, even a small system, even if several authorities were to rule together, this would only be possible if the final decision of one was accepted by the others and subordinated to it. This obedience makes them deprived of authority anyway. If such a situation had occurred in the realm of existence, the other sub-rulers would not have been deities.
The “assistant managers” in the examples given above arise from the top manager’s inability to keep up with every job in terms of time, space, and competence. For Allah, however, none of these limits exist. Allah has a being beyond the boundaries of time and space and has no weakness or difficulty. Therefore, Allah does not need helper deities or to share his divine powers.
The wars and hostilities of even brothers among themselves are evident to seize the administration of countless states in the history of the world. If there was not a single ruler of existence, this peace, tranquility, and order of the universe could not have been preserved until now.
[1] Al-Fatihah /5; Al-Baqarah/163
[2] Abdullah ibn Mas ‘ud (may Allah be pleased with him) reported: I asked the Messenger of Allah (peace and blessings be upon him): “Which sin is greatest?” He said: “That you set an equal to Allah while He alone created you.”(Al-Bukhari,Tefsir,(Furkan)2)
[3] Al-Baqarah/255; An-Nisa/171
[4] Al-Anbya/22