The Holy Spirit has been mentioned in the Quran several times and many questions have been raised about the identity of the Holy Spirit in the Quran. Many of the questions come from our Christian brothers and sisters who wonder if the Holy Spirit in the Quran is the third of their Trinity beliefs.
Quran is very clear in denouncing Trinity (5:73) and affirming the Oneness of God Almighty. (112:1-4). The Holy Spirit in the Quran is clearly defined as the angel Gabriel who has been the angel-messenger between The Almighty God and the human beings, e.g. Mary, Jesus, and prophet Muhammed.
In reference to Gabriel, the Arabic Quran calls him; "Ruhhil-Qudus" (Holy Spirit), "Ruuhanaa" (Our Spirit), "Ruuhul-'Amiin" (The Honest Spirit) and "Al-Ruh' " (The Spirit) . Thus, when reading the verses in the Quran, the whole Quran, we see that Gabriel is the Holy and Honest Bearer of Revelations. We learn from 2:97 that these references are indeed talking about Gabriel.
[2:97] Say, "Anyone who opposes Gabriel should know that he has brought down this (Quran) into your heart, in accordance with GOD's will, confirming previous scriptures, and providing guidance and good news for the believers."
To understand the connection between the Angel Gabriel and calling him the Spirit, the Holy Spirit and the Honest Spirit in the Quran we should also read all related verses, 16:102 & 26:192-193.
[16:102] Say, "The Holy Spirit has brought it (Quran) down from your Lord, truthfully, to assure those who believe, and to provide a beacon and good news for the submitters."
[26:192] This (Quran) is a revelation from the Lord of the universe.
[26:193] The Honest Spirit (Gabriel) came down with it.
Thus, the following verses from the Quran are also talking about Gabriel.
[2:87] We gave Moses the scripture, and subsequent to him we sent other messengers, and we gave Jesus, son of Mary, profound miracles and supported him with the Holy Spirit. Is it not a fact that every time a messenger went to you with anything you disliked, your ego caused you to be arrogant? Some of them you rejected, and some of them you killed.
[2:253] These messengers; we blessed some of them more than others. For example, GOD spoke to one, and we raised some of them to higher ranks. And we gave Jesus, son of Mary, profound miracles and supported him with the Holy Spirit.
[5:110] GOD will say, "O Jesus, son of Mary, remember My blessings upon you and your mother. I supported you with the Holy Spirit, to enable you to speak to the people from the crib, as well as an adult. I taught you the scripture, wisdom, the Torah, and the Gospel.
[19:17-19] While a barrier separated her from them, we sent to her our Spirit. He went to her in the form of a human being. She said, "I seek refuge in the Most Gracious, that you may be righteous." He said, "I am the messenger of your Lord, to grant you a pure son."
[78:38] The day will come when the Spirit and the angels will stand in a row. None will speak except those permitted by the Most Gracious, and they will utter only what is right.
[97:4] The angels and the Spirit descend therein, by their Lord's leave, to carry out every command.
It is interesting that God chose to mention the " Spirit and the angels" in these last two verses . In the Arabic language it is not unusual to specify part of a whole group to emphasize the significance of that part. Quran has many examples like these, e.g.. in 55:68 God talks about fruits, dates and pomegranate to emphasize the last two kinds of fruits.
[55:68] In them are fruits, date palms, and pomegranate.
In 2:238 God talks about Salat and the middle salat to emphasize its significance of the middle salat.
It is also interesting to know that the name " Gabriel" in Arabic (Gbryl) has the same gematrical value of the word "Al-Ruh' " (the Spirit), both being 245. G=3 , B=2, R=200, Y=10 and L=30, therefore 3+2+200+10+30 = 245. While the word Al-Ruh' (The spirit) has , A=1, L=30, R=200, U (waw)= 6 , H'=8, therefore 1+30+200+6+8 = 245
We should also know that the Arabic word "Roh" has been used in the Quran to mean the "revelation from God" as in 16:2, 17:85 and 40:15 and also to mean the soul in many other verses, e.g. 21:91, 66:12, 15:29, 38:72....etc
In conclusion, the "Holy Spirit" in the Quran refers to the angle Gabriel and has nothing to do with Trinity or part of a Trinity. Trinity is denounced in the strongest language in the Quran.