Qul law kana maAAahu alihatun kama yaqooloona ithan labtaghaw ila thee alAAarshi (surah Al Isra: 42)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(17:42) (O Muhammad), tell them that if there had been other deities beside Allah, as they assert, they would surely have tried to find a way to (dethrone) the Master of the Throne. *47

Qul law kaana ma`ahooo aalihatun kamaa yaqooloona izal labtaghaw ilaa zil `Arshi Sabeela

*47) That is, "They would have themselves tried their best to become masters of the Throne". This is because if there had been more than one partners in Godhead, it would produce one of the two results: (1) If they were all independent gods, it was not conceivable that they would agree and co-operate with one another in the management of the boundless universe and there could never have been unanimity, uniformity and balanced proportion in its functioning. There would have been conflict at every step and everyone would have tried to dominate others in order to become its sole master. or (2) if one of them had been the supreme god and the others his obedient servants whom he had delegated some of his powers, then, according to the maxim "power corrupts", they would never have been content with remaining obedient servants of the supreme god and would have conspired to become the supreme god themselves.
Whereas the fact is that in this universe not even a grain of wheat or a blade of grass can grow unless and until everything in the earth and the heavens cooperate with one another for its production. Therefore, only an utterly ignorant and blockheaded person can conceive that there are more than one independent or semi-independent rulers, who carry on the management of this universe. Anyone who has tried to understand the nature and functioning of the universe will most surely arrive at the conclusion that there is One and only One Sovereign ruling over this universe, and there is absolutely no likelihood of any one else to be a copartner in this at any stage.