An explanation surrounding the usage of plural pronouns in the Qurʾān to indicate the greatness of the entity being referred to.
The usage of plural pronouns in the Qurʿān (such as “Indeed, We”) has two purposes in the Arabic language. The first is the widely-known and accepted usage to indicate a single entity who possesses associates in the execution of an act [e.g., the angels, the prophets etc.]. The second is to indicate the greatness of a single deity to whom a multitude of standalone attributes may be ascribed, One who possesses helpers that follow His command, while not being partners unto Him.
So, if the Christians choose to stubbornly persist in the use of verses like:
إِنَّا نَحْنُ نَزَّلْنَا ٱلذِّكْرَ وَإِنَّا لَهُۥ لَحَـٰفِظُونَ
“Verily, We, it is We Who have sent down the Dhikr (i.e. the Qur’ân) and surely, We will guard it (from corruption).”
(Al-Hijr, 15:9)
To evidence their position of worshiping more than one deity [i.e., the trinity], the entirely clear, plainly evident statement to which this issue must be returned are verses like:
وَإِلَٰهُكُمْ إِلَٰهٌ وَاحِدٌ ۖ لَّا إِلَٰهَ إِلَّا هُوَ الرَّحْمَٰنُ الرَّحِيمُ
“And your Ilāh (God) is One Ilāh (God – Allāh), Lā ilāha illā Huwa (there is none who has the right to be worshiped but He), the Most Beneficent, the Most Merciful.”
(Al-Baqarah, 2:163)
And the likeness of such verses that may only be interpreted in a single way, alleviating and dispelling any confusion. For referencing Allāh with plurality in the Qurʿān is meant only to denote the greatness He is most deserving of, the perfection and greatness of His Names and attributes, and the obedience of the angels and other created beings to Him.[1]
There is no difference of opinion among the Arabic linguists, nor among the Muslims themselves, that plural forms of words in Arabic may be used to indicate:
Considering this, we may then acknowledge that Allāh references Himself with plural pronouns in many places in the grand Qurʾān. This plurality is meant only to denote His own greatness, not meant as an indication of multiple entities or that He possesses partners or equals—Glorified and High be He from such great falsehood! For example, His saying:
إِنَّا نَحْنُ نَزَّلْنَا ٱلذِّكْرَ وَإِنَّا لَهُۥ لَحَـٰفِظُونَ
“Verily, We, it is We Who have sent down the Dhikr (i.e. the Qur’ân) and surely, We will guard it (from corruption).”
(Al-Hijr, 15:9)
The plural forms [highlighted above] are not meant to indicate that another entity revealed the Qurʾān with Him, or that another guards it from corruption besides Him—the Most High. Rather, He is the One who has revealed it, and He alone guards it from corruption. Other examples include:
أَفَرَأَيْتُم مَّا تُمْنُونَ ﴿٥٨﴾ أَأَنتُمْ تَخْلُقُونَهُ أَمْ نَحْنُ الْخَالِقُونَ﴿٥٩﴾