Someone might ask: If you claim it is miraculous for the Prophet to bring a book like this when he did it over 23 years, it logically follows that it would be even more miraculous if he did it in one instant. So, why didn’t God reveal the Quran in one go instead of revealing it over two decades?
Allah said: ⟪And those who disbelieve say, “Why was the Qur’an not revealed to him all at once?” Thus [it is] that We may strengthen thereby your heart. And We have spaced it distinctly.⟫ (25:32) and ⟪And [it is] a Qur’an which We have separated [by intervals] that you might recite it to the people over a prolonged period. And We have sent it down progressively.⟫ (17:106)
We can posit several reasons for the Quran being revealed progressively rather than immediately:
One: Whole Law At Once Would Be Overwhelming
If all the laws and teachings of the Quran were revealed at once, it would be overwhelming for people. They would hear the detailed laws and prohibitions and say, “We will never do that,” without ever considering the religion. Thus, revealing it slowly with the foundations and beliefs first and the laws later made it easier for people to accept its message and follow it wholeheartedly. For this purpose, the first verses and surahs of the Quran were revealed to establish people’s faith in God and the Day of Judgement. Extensive laws were only revealed later.
Two: Revelation At Once Would Be Overwhelming to the Prophet (SAW)
The whole Quran being revealed at once would also be overwhelming for the Prophet (SAW). The Prophet already found it difficult to receive verses of the Quran piecemeal. It would be much worse if all of it was revealed at once. Allah said: ⟪Indeed, We will cast upon you a heavy word.⟫ (73:5) and ⟪If We had sent down this Qur’an upon a mountain, you would have seen it humbled and coming apart from fear of Allah.⟫ (59:21) The Prophet was definitely more humble and fearful than a mountain, and it is already a testament to his strength that he withstood the Quran as it was revealed to him.
Three: Gradual Revelation Comforted the Believers
The Quran being revealed repeatedly and almost regularly was a source of comfort for the Prophet (SAW) and the believers. The Prophet (SAW) already found it difficult when the time between two instances of revelation was too much, and Allah revealed ⟪Your Lord has not taken leave of you, [O Muhammad], nor has He detested [you].⟫ (93:3) to comfort him. How much worse would it be if revelation only happened once then never again for the rest of his life? And even if the Prophet himself could get other forms of revelation, the believers around the Prophet mainly had the Quran as their contact with Allah, and Allah speaking to them through the difficult situations they faced helped them get through those situations.
Four: Nurturing of Carriers for the Quran
The Quran being revealed over a period of time ensured that the Prophet (SAW) could build up a group of people who memorized the Quran and wrote it down. He could teach them the Quran as it was revealed, and they would be eager to learn it and write it down because of its novelty. If it was revealed at once, it would be much more difficult to nurture and encourage such a group of people.
Five: Dealing With Different Situations and Contexts
Many Surahs were revealed in certain contexts to evoke different feelings in the Prophet and the general audience, and the Quran being revealed all at once prevents this from happening. For example, some surahs may be revealed to comfort the Prophet (SAW) from sadness and others might be revealed to support him in the face of arguments. All of this would be much less effective if all of the Quran was revealed at once. A new story or statement is more powerful to a person than rereading something he was already told many years ago.
Six: Gradual Nurturing of the Companions
The laws being revealed gradually allowed the early believers and companions of the Prophet (SAW) to naturally grow into the great generation of people they became. By watching how Allah responded to different situations and how the Prophet thought about different problems, they became the most knowledgeable and intelligent group of people in the religion of Islam.
Seven: Real-Time Responses to Queries
The Quran being revealed gradually allowed people to ask the Prophet (SAW) questions so that Allah could respond to them in the Quran itself. Many verses in the Quran respond to questions asked of the Prophet (SAW) in real time. This both allowed for people to establish the veracity of his prophethood by challenging him with questions about things he would not know and allowed the believers to learn about Islamic law and morality in a more interactive manner.
For these reasons I theorized and more reasons which I do not know, Allah decided to reveal the Quran gradually instead of all at once even if that may have seemed more miraculous at first glance. Despite Allah’s choice to do that, the miraculous nature of the Quran is still apparent to the sincere learner.