Ephesians 1:13-14 (NIV) notes:
Having believed, you were marked in him with a seal, the promised Holy Spirit, who is a deposit guaranteeing our inheritance until the redemption of those who are God's possession - to the praise of his glory.
Here the scripture uses the word 'who' which is used to refer to individuals (from my understanding). How does the Greek render the Holy Spirit here in this passage?
The participle translated by the NIV here as 'who' is the Greek word ὅ, which is extraordinarily common and possesses a wide variety of meanings in English. The word is most commonly rendered as 'which' or 'who/whom', and does not by itself indicate whether it's referring to a personal or impersonal subject - we must rely on context for that. So no, this specific word or indeed the passage it sits in does not render the Holy Spirit explicitly as a person.
To stay within the scope of BH.SE we need to focus on the source passage and cannot begin a discussion of other references in the way which your question attempts to.
Disclaimer: My Koine Greek skills are very basic so I welcome any knowledgeable critique of my observations below.
It appears to me that the NIV translation supplied (along with most if not all English translations) misses the meaning of the passage and instead conforms it to Trinitarian dogma. "PNEUMA" ("spirit/breath" (which are synonyms)) is a neuter noun which allows it to be translated along these lines:
"...in which ye were sealed with the holy breath of the promise..."
So what is the "breath of the promise"? The "breath" is inextricably part and parcel of the promise. That is, proclamation of the message of the life, death, resurrection and ascension of Jesus is made by breath:
Weymouth New Testament John 6:63 It is the spirit (breath) which gives Life. The flesh confers no benefit whatever. The words I have spoken to you are spirit (breath) and are Life.
New International Version 2 Cor 3:6 He has made us competent as ministers of a new covenant--not of the letter but of the Spirit (breath); for the letter kills, but the Spirit (breath) gives life.
The notion that breath gives life is not original to either John or Paul (or Jesus) but is an "elementary principle" of the scriptures:
New International Version Genesis 2:7 Then the LORD God formed a man from the dust of the ground and breathed into his nostrils the breath of life, and the man became a living being.
Paul refers to this as "the principle of the breath of life":
BSB Romans 8: 1Therefore there is now no condemnation [death sentence] for those who are in Christ Jesus. 2For in Christ Jesus the law of the Spirit [breath] of life has set you free from the law of sin and death.
So not only do Koine grammar and deeply entrenched scriptural principles argue for the message being in view, so does the immediate context:
NIV Eph 1: 13And you also were included in Christ when you heard the message of truth, the gospel of your salvation. When you believed, you were marked in him [by it] with a seal, the promised Holy Spirit [holy breath of the promise], 14who [which] is a deposit guaranteeing our inheritance until the redemption of those who are God’s possession—to the praise of his glory.
So no, Eph 1:13 is, as I see it, certainly not identifying "the Holy Spirit" as a person. That it appears so in English translations is the result of eisegesis, not an exposition of the Koine, the immediate context or the "pneumatology" of the scriptures.
Update:
Please see my answer to this related post for what is meant by "sealed" which is actually referring to an "inscription": In Eph. 1:13, what does the word "sealed" (ἐσφραγίσθητε) mean?
English mostly uses neuter gender for non living (inanimate) objects. But most other languages including Greek can have gendered pronouns for inanimate objects, it has nothing to with sex and personhood.
The Greek pneuma (spirit or wind) is neuter gender (nothing to do with sex and personhood). The spirit whether holy or evil is naturally and obviously a person or personal entity, a living entity. The idea that the masculine Greek pronoun for pneuma suggests its personhood is purely a 20th century myth created by English speakers, which is clearly developed as an ill-informed apologetic response to the new Unitarian sects or groups which rejected the Holy Spirit's personhood. When you see anomalies in the gender of relative pronouns, it is due to the principle of attraction to the noun's antecedent. For example, the masculine relative pronouns for the neuter spirit in John 14-16 is due to attraction to the masculine "helper/advocate" (parakletos). The focus of the author is on the helper, hence spirit has the masculine pronoun, because it is the advocate.
The linguistic pronoun for the Spirit is always neuter in English, however the new 20th century Bible versions have corrupted it shamelessly, where their religious ignorance and agenda superseded their faithfulness to linguistics. As a result, not only they violated the Spirit's gender in English, but in indefinite other languages, since all other languages get translated through English. The tribal naive nations believe that the scripture explicitly suggests us to violate the linguistic rule for the Holy Spirit, because the British Bible Societies told them to do so. The worst thing is that those who call themselves scholars and translators today lie about this openly to cover this linguistic crime; this is why I feel it is exceedingly important to expose this error.
You will only find those Unitarian sects resisting to this translation blunder, and ironically the Trinitarians follow the myth that anything of neuter gender cannot be a spirit. You will find relevant articles by Unitarians (I am not one of them) on this topic, e.g. IS THE KING JAMES BIBLE IN ERROR TO REFER TO THE HOLY SPIRIT AS "IT"? By Will Kinney
Ephesians 1:14 Greek NT: Westcott and Hort 1881
ὅ ἐστιν ἀρραβὼν τῆς κληρονομίας ἡμῶν, εἰς ἀπολύτρωσιν τῆς περιποιήσεως, εἰς ἔπαινον τῆς δόξης αὐτοῦ.
American Standard Version 1901
which is an earnest of our inheritance, unto the redemption of God's own possession, unto the praise of his glory.
Revised Version 1881
13in whom ye also, having heard the word of the truth, the gospel of your salvation,--in whom, having also believed, ye were sealed with the Holy Spirit of promise,14which is an earnest of our inheritance, unto the redemption of God's own possession, unto the praise of his glory.
Tyndale Bible of 1526
which is the ernest of oure inheritaunce to redeme the purchased possession and that vnto the laude of his glory.
This verse Eph 1:14 has a regular neuter relative pronoun ὅ (ho) for the Spirit, but some later variants and the later unauthoritative texts like Majority Text has ὅς hos. This could have been caused by the scribes mistaking the referent as [masculine] Christ, instead of the Holy Spirit, since the passage is a one continuous long and complicated sentence. Their reason couldn't have been that they believe the Holy Spirit requires a masculine pronoun in Greek, because such a myth developed only among the English speakers of 20th century fanatic people. English being a modern language. I found the Bruce Metzger commentary quote on this verse in a Unitarian site.
The last variant which is in verse fourteen either the reading of ‘o or ‘oV
(ho or hos). A copyist could have altered ‘oV to ‘o in order to make it agree with the gender of pneuma or ‘o could have become ‘oV by attraction to the masculine gender of the following word arrabaon: ἀρραβὼν (guarantee/earnest), according to a usual idiom. The committee opted for the former due to superior external evidence. ‘o is supported by P46 A B F G L P 6 81 104 365 1175 1505 1739 1881 al b d sy-p and Ir-lat, while ‘oV is supported by aleph D Y 33 and the majority text. (3)
Notably, even some rare new translations NABRE and NTE continue to use neuter "it" for the Spirit in Romans 8:16
In some authoritative manuscript witnesses - (Codex Sinaiticus + Byzantine/Majority Text (2000) + Textus Receptus (1551) + Textus Receptus (1894)) - there stands a masculine pronoun ὃς, which would rather suggest the indication of personhood of the πνεύμα, because if you consider πνεύμα as something impersonal, then you will stick strictly to grammar and never use the masculine ὅς but only neuter ὅ.
However, when you regard the πνεύμα as person, then you do not stick strictly to grammar and say "he" (to give an analogy: usually I would write "Luisa came" with a pronoun "she came", for it is a female name, but if I know that "Luisa" is a nickname of a man, then I will write "he came", or if it is a name of my friend's car - "it came"). Thus the very old and authoritative witnesses of the NT codices which put the masculine ὄς must have regarded the πνεύμα as person, for otherwise it is illogical to ruin Greek grammar so stupidly and put the masculine pronoun ὄς for the plainly neuter noun.
Thus, if it is eisegesis, it is not eisegesis of only English translators to put there "who" instead of "which", but already in the beginning of Christianity the Christian scribes regarded the πνεύμα as having the personal characteristics, even if the notion of person (ὑπόστασις) did not exist at that time, but only a latent insight and intuition of this notion, which later, through the Trinitarian and Christological debates of 4th-5th centuries became central to the Western intellectual culture.
And there were multiple very good reasons for attaching the notion of personhood to the Holy Spirit. For example: Matthew ends with "baptize in the name of Father and Son and the Holy Spirit" (28:19), now, if the Father and the Son are persons, it is only reasonable to think the same about the Holy Spirit who stands in the same semantic field in this sentence as the Father and the Son. Or, when Acts 15:28 say that "It seemed good to the Holy Spirit and us": in this clause "us" surely stands for persons and the same verb ἔδοξεν applies to the Holy Spirit, indicating the personhood of the latter and many such passages. And how could the "Holy Spirit" be "another Comforter"? (John 14:16) "Another" stands here with reference to Jesus, so the principal Comforter was Jesus himself, and another Comforter, equal to Him, would be Spirit of Truth, and how would Spirit equal in comforting quality with the person Jesus unless he were person Himself? For by lacking the personhood, no such comforting effect would be conveyed on the disciples saddened by the imminent departure of Jesus from them in the context of this promise. And, again, many other arguments for which I spare my ink and your time for now.
