From a variety of arguments from Scripture it is clear that the fact that "there is one God" must be understood to include God the Father and God the Son. What then is the nature of the Holy Spirit? Is there truly a third Person in the unity that is the Godhead?
That God gives expression to Himself through the Spirit is stated in the first chapter of the Bible: " the Spirit of God moved upon the face of the waters". While perhaps not fully explicit, the wording does imply that an independent "entity" is in action. The Spirit of God is found on several other occasions in the Old Testament to be the means whereby the power of God is brought into play in the life of an individual. The history of Samson in Judges 13-16 speaks of occasions when "the Spirit of the Lord came upon him". It was then that he was able to do astonishing acts of strength. When his head was shaved and he awoke the Scripture simply states, "And he wist not that the Lord was departed from him" (Judg 16.20). In addition to noting that here again we find the kind of action we expect from a person rather than a vague "influence", it seems clear from these verses that the "the Spirit of the Lord" is none other than "the Lord". The Spirit has the character of a Person who is Jehovah.
Our attention is drawn again to the Spirit acting as an independent Person when, after Davids anointing by Samuel, "the Spirit of the Lord came upon David from that day forward" while "the Spirit of the Lord departed from Saul" (1 Sam 16.13,14). It is worth noting that this work of the Spirit in Davids experience did not make him perfect in behaviour. Like Saul before him he was not always obedient and the Spirit of God was no doubt grieved thereby.
From examples like these it is evident that something more than "Gods influence at a distance" is in view. This "Spirit" is not merely another name for the power of God, but is Himself One who brings with Him the power of God into the experience of the person upon whom or into whom He comes.
Is this consistent with the New Testament? Of the Spirit of God the Scripture states that He speaks (Acts 13.2) as one who gives Gods instructions to the church at Antioch, reveals (Lk 2.26) to Simeon that he would continue to live until he had seen "the Lords Christ", witnesses (Acts 5.32) concerning the Lord Jesus as one whom God has given "to them that obey him", knows (1 Cor 2.10,11) the things of God while men cannot do so, sends (Acts 13.4) men out to work for God, appoints (Acts 20.28) overseers to feed the church of God, instructs (Acts 15.28) the church at Jerusalem on how Gentiles ought to behave, can be grieved (Eph 4.30), and can be resisted (Acts 7.51). These references demonstrate the characteristics of a sentient person, busy in the experience of individuals in doing a variety of tasks that an "influence" could not be described as doing. He ought to have a major influence but is not to be defined as an influence.
The fullest account of the Person and work of the Spirit is found in the teaching of the Lord Jesus to His disciples. The disciples were troubled (not unreasonably) by the thought that the Saviour would not continue to be with them day-by-day as He had been for the previous three years. He had stated clearly that He was going away from them. However, He promises them that He "will pray the Father and he shall give you another Comforter, that he may abide with you for ever; Even the Spirit of truth" (Jn 14.16,17). From these and later verses it is certain that "the Comforter" is a Person of like nature to the Lord Jesus Himself. He will therefore be able to compensate them for the absence in heaven of the Saviour. He is "the Spirit of truth" and later (v.26) is described as being holy. He is "the Comforter, which is the Holy Ghost" (of course, "Ghost" is better translated as "Spirit").
The Lord Jesus, we have earlier seen, is described as "that holy thing that shall be born of thee" (Lk 1.35), and so the holiness of God is, as one would expect, a characteristic of the Son of God. Now we learn that holiness is also part and parcel of the nature of the Spirit of God. He is "the Holy Spirit". With this in mind it is as we expect when we find that elsewhere He is described as "the eternal Spirit" (Heb 9.14), and so is possessed of another essential feature of deity.
What is true is that the Holy Spirit is not seen. The Son is the visible expression of God. Invisible but vital, the Spirit has, for example, as part of His work, the disciples were told, to "teach you all things, and bring all things to your remembrance, whatsoever I have said unto you" (Jn 14.26). That He did indeed do this is seen in the writing of the Gospels and is consistent with a previous work of His noted by Peter in relation to the Old Testament when "holy men of God spake as they were moved by the Holy Ghost" (2 Pet 1.21).
The invisible but powerful work of the Spirit is emphasised by the Lord Jesus to Nicodemus as described in John 3. The Saviour speaks of the need to be "born again". Now what is required is not simply a spiritual birth as opposed to a natural one, but rather being born "of the Spirit". That is to say that the Holy Spirit is the active agent of God in bringing new life. The parallel between John 1.13 - "born of God", and John 3.6 - "born of the Spirit", brings this into focus. Ezekiel was given a glimpse of this truth when he saw the vision of the valley of dry bones. "Can these bones live?...(I) shall put my Spirit in you, and ye shall live" (Ezek 37.3,14). Here the prophet learns that it is the entry of the Holy Spirit that brings life. That the indwelling Spirit as a bringer of spiritual life is a recurring theme in the New Testament is no surprise.
The Holy Spirit is therefore brought before us as One who has all the features of independent personality and of deity. He is God the Holy Spirit.
Our response to the Holy Spirit ought to be obedience. In several of the passages referred to above He instructs and guides. However, as we also noted, He can be grieved and resisted. Not only can this be true as a remote possibility, it does happen in all our experiences. How much we lose as a result!
So "There is one God". But God is not "lonely"! The God of the Bible, both of the Old Testament and the New reveals Himself to us in three Persons who are yet a single unity. There is communion, communication, and love within deity. The three are brought together for us from time-to-time in Scripture. Before His return to heaven the Lord Jesus instructs His followers to "Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost" (Mt 28.19). It would be odd exegesis indeed that claimed that only one or perhaps two were persons and that only one or perhaps two were fully possessed of the same divine nature and were fully God.
In similar fashion the benediction at the close of 2 Corinthians brings the three together, albeit with different aspects of their character mentioned in a single blessing that surely resonates with the words of Numbers 6.24-26. In that passage Aaron is commanded to "put my name upon the children of Israel; and I will bless them". A threefold blessing fits well with a threefold name for God in His Trinity of being. From Paul we have "The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Ghost, be with you all" (2 Cor 13.14).
As emphasised elsewhere in these articles we cannot explain God, we simply try to understand and believe His revelation of Himself (and we have the help of the Holy Spirit to do so). Then, in the light of that, we ought to behave in a manner that can truly be described as walking "after the Spirit" (Rom 8.1).
To be continued.