It should however be obvious even from the quotations given that it is essential for proper comprehension of the teachings of the Qur'ān fully to understand the implications of these four terms. The Qur'ān will in fact lose its whole meaning for anyone who does not know what is meant by ilaah or rabb, what constitutes ’ibadah, and what the Qur'ān means when it uses the word deen. He will fail to learn what Tawhid (belief in the One-ness of Allah in the fullest sense) is, or what constitutes its anti-thesis, that is, shirk (the attribution to others, either wholly or partially, of any of Allah’s exclusive qualities or attributes).

It will not be possible for him to make his ’ibadah, or his deen, exclusive for Allah alone. And little better than such a completely ignorant man would be the one who has only a vague idea of what the terms imply, because in that case the whole teaching of the Qur'ān will remain vague and incomplete for him, and both his belief and his conduct will fatally leave much to be desired. He will no doubt keep on reciting the words of the kalimah, and even explain that it means that there is no ilaah but Allah, and yet, in practice, he will keep treating many another to be an ilaah too. He will go through life proclaiming that there is no rabb but Allah, and yet for all that there will be many whom he will be treating as rabbs. He will protest, and affirm, with all seriousness and sincerity, that he does not give his ’ibadah to any but Allah, and will yet keep giving to others unknowingly. If anyone even so much as hints that he has any other deen, he would feel offended enough to come to blows with the accuser, and yet in practice, he will unwittingly be giving his allegiance to many another deen.

No one will ever hear him actually use the words Allah or rabb in respect of any but in the specific sense in which the words have been employed in the Qur'ān, but he will be conducting himself as if he had many an ilaah and many a rabb though without realising this, just like the person who never realised until he was specifically told that he had been uttering prose all his life. If someone were to tell him in so many words that he was giving his ’ibadah to others, and thus committing shirk, he might resent this strongly and even quarrel violently, but according to the criteria applicable he will unconsciously have been living as a worshipper of others as an adherent of the deens of others, without ever suspecting that in fact was the case.