Why Does Allah (swt) Refer to Himself as We/He?

We already know Allah our lord is One. As in Surah al-Ikhlas 112:1-4. But why does Allah the Lord use the word “We” to refer to Himself in many verse or ayat in the Qur’an? For example He says in Surah al-Anbiya’ 21:107 “And We did not send you (O Muhammad) except as a mercy to the world.” The word “we” is plural, more than one. Why does Allah use “We” instead of “I” to refer to Himself?
Answer:
It is a feature of literary style in Arabic that a person may refer to themself by the pronoun nahnu (we) for respect or glorification. They may also use the word ana (I), indicating one person, or the third person huwa (he). All three styles are used in the Qur'an, where Allah addresses the Arabs in their own tongue.

Allah, the Glorified and Exalted, sometimes refers to Himself in the singular, by name or by use of a pronoun, and sometimes by use of the plural, as in the phrase (interpretation of the meaning):

"Verily, We have given you a manifest victory." [al-Fat'h 48:1], and other similar phrases.

But Allah never refers to Himself by use of the dual, because the plural refers to the respect that He deserves, and may refer to His names and attributes, whereas the dual refers to a specific number (and nothing else), and He is far above that." (See Al-'Aqeedah al-Tadmuriyyah by Shaykh al-Islam Ibn Taymiyyah, p. 75.)

These words, inna "Verily We" and nahnu "We", and other forms of the plural, may be used by one person speaking on behalf of a group, or they may be used by one person for purposes of respect or glorification, as is done by some monarchs when they issue statements or decrees in which they say "We have decided…" etc. [This is known in English as "The Royal We"]

In such cases, only one person is speaking but the plural is used for respect. The One Who is more deserving of respect than any other is Allah, the Glorified and Exalted, so when He says in the Qur'an - inna "Verily We" and nahnu "We", it is for respect and glorification, not to indicate plurality of numbers.

If an 'aayah (verse) of this type is causing confusion, it is essential to refer to the clear, unambiguous 'aayat (verses) for clarification, and if a Christian, for example, insists on taking 'aayat such as (interpretation of the meaning) "Verily, We: it is We Who have sent down the Dhikr (i.e., the Qur'an)…" [al-Hijr 15:9] as proof of divine plurality, we may refute this claim by quoting such clear and unambiguous 'aayat as (interpretation of the meanings): "And your God is One God, there is none who has the right to be worshipped but He, the Most Beneficent, the Most Merciful." [al-Baqarah 2:163] and "Say: He is Allah, the One." [al-Ikhlas 112:1] and other 'aayat which can only be interpreted in one way. Thus confusion will be dispelled for the one who is seeking the truth.

Every time Allah uses the plural to refer to Himself, it is based on the respect and honor that He deserves, and on the great number of His names and attributes, and on the great number of His troops and angels." (See Al-'Aqeedah al-Tadmuriyyah by Shaykh al-Islam Ibn Taymiyyah, p. 109.)

Alternate Answer:

This is a good question and one that Bible readers have also asked about. The term "We" in the Bible and in the Quran is the royal "We" - as an example when the king says, "We decree the following declaration, etc." or, "We are not amused." It does not indicate plural; rather it displays the highest position in the language. English, Persian, Hebrew, Arabic and many languages provide for the usage of "We" for the royal figure. It is helpful to note the same dignity is given to the person being spoken to in English. We say to someone, "You ARE my friend." Yet the person is only one person standing there. Why did we say "ARE" instead of "IS"? The noun "you" is singular and should therefore be associated with a singular verb for the state of being, yet we say, "are." The same is true for the speaker when referring to himself or herself. We say, "I am" and this is also in the royal plural, instead of saying, "I is."

When Allah uses the term "HE" in Quran it is similar to the above answer. The word "He" is used when referring to Allah out of respect, dignity and high status. It would be totally inappropriate to use the word "it" and would not convey the proper understanding of Allah being who Allah is; Alive, Compassionate, Forgiving, Patient, Loving, etc. It is not correct to associate the word "He" with gender, as this would be comparing Allah to the creation, something totally against the teaching of Quran.