Our article on Jesus as God's Wisdom is a defense of the doctrine of the Trinity defining the Father-Son relationship against heretical interpretations. But what about the Holy Spirit, the "quiet third" of the Trinity -- whose role at times seems so muted that the danger, unlike with the Son, is not in removing the Spirit's deity, but rather his personality?
I found, as I did in the case of Jesus and Wisdom, a Jewish conceptual category that fit the Holy Spirit, and also discovered that where the Holy Spirit is concerned, Christianity took a radical departure from their Jewish forebears.
My programmatic source for this essay is James D. G. Dunn's Christ and the Spirit, Vol. 2 on pneumatology. Dunn's first volume dealt with Christ and the second assumes knowledge of the first, as I here assume knowledge of my Wisdom essay linked above. The "shock" to our system is this: if the NT writers had followed their Jewish forebears regarding the Holy Spirit as they followed them on Wisdom, we would not today be Trinitarians but Binatarians, for "before the incarnation Logos and Spirit were hardly to be distinguished." 
But let's begin not with the time between the Testaments, but with the OT itself, and with some commentary on the role and purpose of the Holy Spirit.
We begin with these quotes from the OT:
Gen. 1:2 And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.
This verse contributes our first glimpse for understanding: The word "spirit" is the Hebrew ruwach, and it is the usual word for any spirit, human or divine, but it is also the word used for wind (Genesis 8:1 God made a wind to pass over the earth, and the waters asswaged...)
The clue we gather here is that "spirit" is a moving and active thing -- not stagnant. We will see the application of this later on.
Exodus 31:3 And I have filled him with the spirit of God, in wisdom, and in understanding, and in knowledge, and in all manner of workmanship...
Here the Spirit of God is tied directly to the possession of wisdom and knowledge. (See also Ex. 35:31) We can already sense that there will be a close relationship between Wisdom and the Spirit. But the Spirit is responsible for other types of insight as well:
Numbers 24:2 And Balaam lifted up his eyes, and he saw Israel abiding in his tents according to their tribes; and the spirit of God came upon him.
The Spirit of God is also tied in with prophecy. The alert reader will anticipate that this carries over into NT times as well. (See also 1 Sam. 10:10, 2 Chr. 24:20, Ezek. 11:24) But we will also see that there is a synonym for the Spirit in the context of prophectic activity:
1 Kings 18:46 And the hand of the LORD was on Elijah; and he girded up his loins, and ran before Ahab to the entrance of Jezreel.
Is. 8:11 For the LORD spake thus to me with a strong hand, and instructed me that I should not walk in the way of this people...
Jer. 15:17 I sat not in the assembly of the mockers, nor rejoiced; I sat alone because of thy hand: for thou hast filled me with indignation.
Ezekiel 1:3 The word of the LORD came expressly unto Ezekiel the priest, the son of Buzi, in the land of the Chaldeans by the river Chebar; and the hand of the LORD was there upon him.
The imagery of God's "hand" is found in these passages associated with prophecy; but it is also found in other contexts which give us further insight:
Deut. 2:15 For indeed the hand of the LORD was against them, to destroy them from among the host, until they were consumed.
1 Sam. 12:15 But if ye will not obey the voice of the LORD, but rebel against the commandment of the LORD, then shall the hand of the LORD be against you, as it was against your fathers.
These are examples of places where "hand" is used to refer to activity or action as a whole, as it is in these examples:
Gen. 16:6 But Abram said unto Sarai, Behold, thy maid is in thy hand; do to her as it pleaseth thee.
Ps. 31:15 My times are in thy hand: deliver me from the hand of mine enemies, and from them that persecute me.
The hand signifies action and power. The "hand of God" signifies God's action and power. This lays the foundation for an understanding of the Holy Spirit as God's action principle in the world (which acts in accordance with God's Word, or instruction).
There is a final set of quotes we need to look at:
Judges 3:10 And the spirit of the LORD came upon him, and he judged Israel, and went out to war: and the LORD
Judges 11:29 Then the spirit of the LORD came upon Jephthah, and he passed over Gilead, and Manasseh, and passed over Mizpeh of Gilead, and from Mizpeh of Gilead he passed over unto the children of Ammon.
Judges 15:14 And when he came unto Lehi, the Philistines shouted against him: and the spirit of the LORD came mightily upon him, and the cords that were upon his arms became as flax that was burnt with fire, and his bands loosed from off his hands.
2 Kings 2:16 And they said unto him, Behold now, there be with thy servants fifty strong men; let them go, we pray thee, and seek thy master: lest peradventure the spirit of the LORD hath taken him up, and cast him upon some mountain, or into some valley. And he said, Ye shall not send.
Isa. 40:7 The grass withereth, the flower fadeth: because the spirit of the LORD bloweth upon it: surely the people is grass.
Is. 61:1 The spirit of the Lord GOD is upon me; because the LORD hath anointed me to preach good tidings unto the meek; he hath sent me to bind up the brokenhearted, to proclaim liberty to the captives, and the opening of the prison to them that are bound;
The "spirit of the Lord" is another synonym for the divine principle that inspires prophecy and inspires action.
We are now ready to look at what commentary is available from between the Testaments. As noted, and in accordance with the first Exodus quote above, there appears to have been no distinction made between God's Wisdom and God's Spirit:
Wisdom of Solomon 9:17 Who has learned thy counsel, unless thou hast given wisdom, and sent thy holy spirit from on high?
As Dunn notes, Wisdom/Logos and Spirit overlap. This is also found in Philo (De plantatione 18).
Our study now moves to the NT evidence, and it is here where we encounter our key issue of diversion from Christianity's Judaistic roots. Christianity developed a "bifurcation" between the Wisdom and the Spirit that was not paralleled in Judaism; and yet, we also see that a close relationship remains between the two.
Let's work through the NT and see how the "Holy Ghost" (as it reads in the KJV) parallels the role of the Spirit or hand of God in the OT.
Matthew 3:11-12 I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost, and with fire: Whose fan is in his hand, and he will thoroughly purge his floor, and gather his wheat into the garner; but he will burn up the chaff with unquenchable fire.
Luke 1:35 And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God.
Here the Holy Spirit is associated with God's actions -- in judgment and cleansing, in creative power. (Note especially the parallel to Is. 40:7.)
Matthew 16:17 And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven.
Mark 12:36 For David himself said by the Holy Ghost, The LORD said to my Lord, Sit thou on my right hand, till I make thine enemies thy footstool.
Luke 1:15 For he shall be great in the sight of the Lord, and shall drink neither wine nor strong drink; and he shall be filled with the Holy Ghost, even from his mother's womb.
Luke 1:67 And his father Zacharias was filled with the Holy Ghost, and prophesied...
John 14:26 But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.
Jonn 15:26 But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, he shall testify of me...
Here the Holy Spirit is associated with prophetic inspiration, and with knowledge imparted by God. However, it is possible to read too much into this; the Spirit is not a dispenser of propositional truth. There is also no indication that such revelation is normative for the Christian, nor that the Spirit reveals any and all things we might want to know.
As we move into the post-resurrection church, these roles paralleling the OT continue -- and we also see a tight relationship between Word and Spirit:
Acts 2:17-18 And it shall come to pass in the last days, saith God, I will pour out of my Spirit upon all flesh: and your sons and your daughters shall prophesy, and your young men shall see visions, and your old men shall dream dreams: And on my servants and on my handmaidens I will pour out in those days of my Spirit; and they shall prophesy:
Here Peter has explicitly connected the Holy Spirit with the prophetic and eschatological spirit reported in Joel. But now see an example of the "tight relationship":
Acts 6:3 Wherefore, brethren, look ye out among you seven men of honest report, full of the Holy Ghost and wisdom, whom we may appoint over this business.
Compare this to the Exodus cite above.
Acts 2:37 Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do?
The Spirit is not mentioned here, but this is a good place to note that in a time and place before what we call "conscience" was known (see here) it is possible that the Spirit operated in the same sense as a conscience would for us.
Acts 13:4 So they, being sent forth by the Holy Ghost, departed unto Seleucia; and from thence they sailed to Cyprus.
Compare this to OT passages above from Judges.
Acts 28:25 And when they agreed not among themselves, they departed, after that Paul had spoken one word, Well spake the Holy Ghost by Esaias the prophet unto our fathers...
The Holy Spirit is identified with the Spirit of God in the OT that inspired prophecy.
1 Cor. 12:3 Wherefore I give you to understand, that no man speaking by the Spirit of God calleth Jesus accursed: and that no man can say that Jesus is the Lord, but by the Holy Ghost.
The Spirit here offers an "experiential identification" [Dunn, 79] with Christ for the believer. Through the Spirit, the believer experiences Christ; yet they are still distinct. Another relevant contribution:
Romans 8:9-11 But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
Here the "Spirit of God" and "Spirit of Christ" are synonymous. Now another "role" verse for the Spirit:
1 Cor. 6:11 And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God.
1 Peter 1.2: who have been chosen according to the foreknowledge of God the Father, through the sanctifying work of the Spirit, for obedience to Jesus Christ and sprinkling by his blood
The Spirit is a washer, a justifier, a sanctifier. It is God's principle of action, and "the medium by which Christ is known to and united with his followers." [Dunn, 337]
So it is clear by now that the NT teaches an equation of the Holy Spirit with the Spirit, or hand, of the Lord/God in the OT. This emerges quite clearly in these parallel verses:
Matt. 12:28 But if I cast out devils by the Spirit of God, then the kingdom of God is come unto you.
Luke 11:20 But if I with the finger of God cast out devils, no doubt the kingdom of God is come upon you.
Luke here is clearly influenced by the passage in Exodus in which the magicians of Pharaoh, defeated, attribute miraculous power to the "finger of God." But we can also see a relationship overall to passages speaking of the "hand" of God. Furthermore, note that the presence of the kingdom of God is determined in terms of the "effective power of the Spirit" [Dunn, 6]. In essence, the Spirit's presence signifies the presence of God's ruling power.
The divinity of the Holy Spirit is not in question based on the Scriptures. It is also clear from the Wisdom connection that the Spirit is in relation to God in a thoroughly Trinitarian sense -- it is not a separate being, but like Wisdom, proceeds from God. (There is some discussion over exactly how this procession works, but that is an issue we will leave aside for the present.)
There remains one question: can it be shown that the Holy Spirit is a person as Jesus the Word was? Is it justified to see the Spirit as a "distinct center of conscious thought" as the creedal statements affirm?
At first glance, it may be easy to object that with no incarnation of the Spirit, there is no direct evidence of the Spirit as a person. The Spirit could just be a "force with you" and impersonal, an effect of God. Why not be a Binitarian? There are no statements, as from Jesus, where the Spirit prays to the Father. Or are there?
Romans 8:26 Likewise the Spirit also helpeth our infirmities: for we know not what we should pray for as we ought: but the Spirit itself maketh intercession for us with groanings which cannot be uttered.
If the Spirit is not a separate person, how does he intercede? But here is the classic text for the personhood of the Spirit:
Acts 5:3, 9 But Peter said, Ananias, why hath Satan filled thine heart to lie to the Holy Ghost, and to keep back part of the price of the land?...Then Peter said unto her, How is it that ye have agreed together to tempt the Spirit of the Lord? behold, the feet of them which have buried thy husband are at the door, and shall carry thee out.
Is it possible to lie to or test, to disobey or to grieve, an impersonal force? (See also Acts 16:16, Eph. 4:30) Or:
John 16:13 Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will show you things to come.
Acts 13:2 As they ministered to the Lord, and fasted, the Holy Ghost said, Separate me Barnabas and Saul for the work whereunto I have called them.
Acts 15:28 For it seemed good to the Holy Ghost, and to us, to lay upon you no greater burden than these necessary things...
Hebrews 3:7 Wherefore as the Holy Ghost saith, To day if ye will hear his voice...
1 Tim. 4:1 Now the Spirit speaketh expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils;
Luke and Darth's "Force" didn't have anything to say, but the Spirit does, and even uses personal pronouns (Acts 13:2).
Objection: The Bible has trees speaking [Ps. 96:11-12; Is. 55:12], and hands and feet speaking [1 Cor. 12:15-16]. It also has names rotting [Prov. 10:7], land vomiting [Lev. 18:25] and blood crying out [Gen. 4:10]. So what if the Spirit speaks also?
This objection doesn't work: These passages are clearly in poetic/allegorical genres, whereas the above verses are straight narrative discourse; furthermore, verses where land vomits or blood cries is also clearly allegorical, since land and blood have no mouth, but a spirit is a living and active force and has a means to speak.
At the same time, neither land nor blood ever has such a wide variety of active and interpersonal-relation verbs applied to them. Blood cries out, but no one has ever "lied" to blood or had it intercede for them in prayer. The Spirit is indeed the quiet member of the Trinity in terms of the reports we have; he was not incarnated among men and converses with them even now only inwardly. But he clearly does speak, and that's not what an impersonal force does.
1 Tim. 2:5 says, For there is one God, and one mediator between God and men, the man Christ Jesus. If the Holy Spirit were a person co-equal with the Father and Son it would be an affront to exclude him from some intermediary position.
This objection simply doesn't grasp the meaning of the term "mediator". It was originally a business term, broadened to mean any mediator. The word is used by Paul elsewhere to refer to Moses (Gal. 3:19) and in Hebrews 1:6: "But now hath [Jesus] obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises." (See also 9:15, 12:24)
The word refers to a specific function of administration, not merely a go-between. The Spirit did not and does not serve this function.
The word "spirit" is neuter in gender. How can an "it" be a person?
John's Gospel twice refers to the Holy Spirit in a masculine gender: 15:26 But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, he shall testify of me: John 16:13 Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will show you things to come. Helpfully the last passage also clarifies the nature of the relationship of the Spirit to the Father; the Spirit "proceeds" as Wisdom does.
But other objects are assigned gender in the Bible. Even today we refer to objects like ships in the feminine.
Those who offer this objection -- which I have found -- fail to provide examples of objects in the Bible being assigned gender. The idea about ships has no bearing unless one provides evidence that a "spirit" was referred to thusly even without any notion of personality. However, we might add that many languages assign gender to inanimate objects, so this is a non-issue anyway.
Finally, there are Trinitarian formula which place the Spirit on a par with Father and Son (Matt. 28:19, 2 Cor. 13:14). Some may object that there is nothing that says that the Spirit is a person in these passages, but it is the burden of proof upon the replier to show that personality is not part of the Spirit's makeup.