Ilaah, Rabb, Deen and ’Ibadah, are four terms basic to the whole teaching of the Qur'ān. Throughout its pages, it stresses again and again that Allah Almighty is the Rabb and the Ilaah; that there is no ilaah but He, nor is there any other rabb, nor does He share with anyone else the qualities and attributes implied by these terms. He, and He alone should therefore be accepted as one’s Ilaah and Rabb, and no one else should in the least be believed to possess the attributes which these words imply. It also demands that we should give our ibadah to Him and Him alone, and not to anyone else, and make our deen exclusive to Him and reject all other deens!

The verses quoted above are just by way of example, and not the only ones of their kind. Whosoever makes more than a cursory study of the Qur'ān will soon realise that the entire contents revolve round these four terms only, and that the central idea of the whole book is that: Allah is the Rabb, and the Ilaah; No one else possesses the qualities and attributes implied by these terms; Wherefore men should give their ’ibadah to Him and Him alone; and one’s deen should be exclusively for Him with no share of it for any other.