Answer
In the Name of Allah, Most Gracious, Most Merciful.
All thanks and praise are due to Allah and peace and blessings be upon His Messenger.
Dear questioner! Thanks for your good question that reflects great keenness on understanding the teachings of Islam and having a comprehensive answer to the claims of its opponents.
Most of the scholars of semantics said: The Qur’an was revealed in the language of the Arabs, and it is their way to repeat things for emphasis and to ensure that they are understood, and also to speak briefly so as not to tire the listener, because when the speaker uses different phrases in his speech, it is better than limiting himself to one phrase.
Being the Muslim’s Glorious Book and the final testament given to all people to show them the Straight Path of righteousness, the Qur’an stands as an inimitable divine book directing all people to the best of deeds and showing them how to worship their Lord and run their affairs according to His will so as to gain in this world as well as in the afterlife. It is thus natural to say that the Qur’an aims at guiding mankind from the time of its revelation to the Day of Resurrection.
The Qur’an is a discourse issuing from, first of all, the greatest and most comprehensive rank of the universal Lordship of the Eternal Speaker, and is addressed, first of all, to the comprehensive rank of the one who received it in the name of the universe.
It aims at the guidance of the whole of mankind from the time of its revelation to the end of time, and contains entirely meaningful and comprehensive explanations about the Lordship of the Creator of the universe and the Lord of this world and the Hereafter, the earth and the heavens, and eternity, and about the Divine laws pertaining to the administration of all creatures.
This discourse is so comprehensive and elevated, and therefore so inclusive and miraculous, that even the apparent and simplest level of its teaching directed at the understanding of common people who constitute the great majority of its addressees, perfectly satisfies those of the highest level of understanding.
However frequently the Qur’an is recited, it does not bore or fatigue:
The Qur’anic miraculous expression revives all past time which, in the view of heedlessness and misguidance, is a lonely and frightful realm and a dark, ruined cemetery, and transforms all the past, dead ages and centuries into each a living page of instructions, a curious, animated realm, under the direct control of the Lord, a realm which has significant relations with us.
Like the motion pictures, by either taking us over to those times or bringing them over before us and showing them to all, the Qur’an gives us its lessons in its elevated miraculous style and again in the same style it changes the universe, which is, in the view of misguidance, an unending, lifeless, lonely and frightful place rolling in decay and separations, into a book of the Eternally Besought-of-All, a city of the Most Merciful One, a place of the exhibition of the works of the Lord’s art, where lifeless objects become animate beings doing their particular duties and helping one another in a perfect system of communication.
The Qur’an demonstrates itself also to be a book of supplications and invocations, and a call to eternal salvation and declaration of Allah’s Unity, all of which require reiterations.
Therefore, through agreeable reiterations, it offers in a single sentence or a story, numerous different meanings to many different groups or categories of its addressees, and treats with compassion even the smallest and most slight things and events and includes them in the sphere of its will and control.
Satisfying recurring needs requires reiteration:
The repetition of needs requires reiterations. Also, the Qur’an answers many questions repeatedly asked during twenty years of its revelation and seeks to satisfy all levels of understanding and learning.
Again, in order to prove that all things particular or universal from particles to stars are at the free disposal of a Single One Who will utterly destroy the whole universe to exchange it with the wholly extraordinary world of the Hereafter, and in order to establish in minds a mighty and all-comprehensive revolution which will demonstrate the Divine wrath in the name of the results of the creation of the universe, in the face of the injustices and wrongdoing of mankind which make the universe, the earth and the heavens angry and bring them to fury, the Qur’an repeats some sentences and verses which are the conclusions of innumerable proofs and have as great weight as thousands of conclusions.
So, making repetitions for the purposes mentioned, rather than being a defect, must be, and indeed it is, an extremely powerful aspect of miraculousness, an extremely elevated virtue of eloquence, and a beauty of language in conformity with the requirements of the subject matter.
Establishing truths in minds requires reiteration:
For example: The phrase: ‘In the Name of Allah, Most Gracious, Most Merciful.’, which comes at the beginning of every Sura (except one), and together with that in Sura An-Naml, is repeated one hundred and fourteen times in the Qur’an, is a truth which links the earth to Allah’s Supreme Throne and all the spheres of the universe together, and illuminates the universe, and which everybody always needs, so that it is worth repeating millions of times. We need it not only every day like bread but also at every moment as we need air and light.
Also, the verses: “Which of Your Lords bounties will you two deny?” and: “Woe on that day to the deniers!” which are repeated several times in Surat Ar-Rahman and Surat Al-Mursalat respectively, exclaim before the earth and the heavens and the ages, and in the face of men and jinn, their ingratitude, unbelief and wrongdoing, and their violation of the rights of all other creatures, which bring the heavens and the earth to rage, spoil the results of the creation of the universe, and indicate contempt and denial of the majesty of Divine Sovereignty.
If in a universal teaching which is related to thousands of issues these two verses were repeated thousands of times, still there would remain need for them and it would be a conciseness in majesty and a miraculousness of eloquence in grace and beauty.
Thus, it is because of certain essential needs and realities such as those that the Qur’an makes reiterations. Sometimes it even happens that as occasion requires, eloquence demands, and to facilitate understanding, it expresses the truth of Divine Unity twenty times in a single page explicitly or implicitly. It causes no boredom; rather, it enforces the meaning and gives encouragement.
The Makkan Surahs, and those revealed in Madinah are different from each other in eloquence and miraculousness, and with respect to elaboration or conciseness. This is because, since those the Qur’an addressed in Makka were mainly the polytheists, it would have to use a forceful, eloquent and concise language with an elevated style and make reiterations to establish its truths.
The Makkan Surahs repeatedly express the pillars of faith and the forms or categories of the Divine Unity in a forceful, emphatic, concise and miraculous language, and not only in a page or a verse or a sentence or a word, but also in a letter or in changing places of the words in a sentence or in using definite articles or omission of articles, or mentioning or omission of certain words or phrases or even sentences, they prove the beginning and the end of the world, the Divine Being and the Hereafter in so powerful a way that geniuses of the science of eloquence have been amazed at it.
The Qur’an being both a book of law and wisdom and a book of creeds, belief, reflection, invocations, prayer and call to the Divine Message require repetition or reiteration. Indeed, while explaining the secondary principles and social laws of Islam, the Qur’an abruptly draws the attentions of its addressees to elevated, universal truths, and from the lesson of the Shari`ah to the lesson of Divine Unity, and changes from a plain style to an elevated one, thus showing itself to be both a book of law and wisdom and a book of creeds, belief, reflection, invocations, prayer and call to the Divine Message.
By offering its aims of guidance on every occasion, the Qur’an displays in its Madinan Surahs a brilliant miraculousness of eloquence and purity of language different from the styles of the Makkan Surahs.
It sometimes occurs that in two words, for example, in the Lord of the Worlds and your Lord, it declares the manifestation of Allah’s Names in all creatures, and their manifestation in a single being respectively; it expresses the former within the latter. Sometimes it even happens that where it fixes a particle in the pupil of an eye, it fixes with the same ‘hammer’ the sun in the heaven and makes it an eye of the heaven.
Almighty Allah knows best.
Excerpted, with slight modifications, from: www.thewaytotruth.org