The Doctrine of the Holy Trinity: Historical Development

By H.B. Mar Meelis Zaia, A.M.
Metropolitan of the Assyrian Church of the East
Archdiocese of Australia and New Zealand

In the Old Testament

Throughout the ages the Christian Church has always believed in God as three in ONE, and this belief is based on the Bible. Although the main evidence  for  the  doctrine  of  the  trinity  is  to  be  found  in  the  New Testament,  we  need  to  start  with  the  Old  Testament.  We must  never forget  that  the  New Testament  is  based  on  the  Old.    No  statement  of  belief  is complete,  unless  it  is  seen  within  the  context  of  the  whole  Bible, including the Old Testament.

When we study the Old Testament, one thing immediately stands out: the main emphasis is on the unity of God. As far as His Godhead is concerned He is alone, unique.   The oneness of God is the central confession of all Christians, as we recite  in the Nicene Creed of 325 AD,”We believe in One God”.

Careful  reading of the Old Testament shows  no indication  of the trinity itself. Yet there are several  remarkable aspects,  which definitely have to be taken into account, if we want to see the full picture of the Old Testament understanding of God.

As  we said  before, in the  Old  Testament,  the first  imperative  was to declare the existence of the ONE living and true God. And to this task the Old Testament is principally dedicated. And this principal is the fundamental faith of the Christian religion.

Hear, O! Israel: The LORD our God, the LORD is one! (Deuteronomy:6:4)


Have we not  all  one  father?  Has not one  God  created  us? (Malachi 2:10)

But there are also passages where God speaks  of himself  in the Plural, especially  in the opening  pages of the Old Testament. Based on this, Christians  are taught to attribute the existence and persistence of all things to a threefold source. For example, there are passages where the Lord God, his Word and  his Spirit  are  brought  together  as in  the  narrative  of  the creation where God is seen to create by means of his Word and Spirit:

And the Spirit of God was hovering over the face of the waters. Then God said, “ Let there be light“; and there was light.  (Genesis 1:2-3)

Also, the next passages points in the same direction:

Then  God  said,  “ Let  us  make  man  in  our  image  according  to  Our likeness”  (Genesis I :26).

Then the Lord God said, “ Behold, the man has become one of Us”  (Genesis 3:22)

Other  references  to  the same  is Genesis 2:7

“Come,  let Us go down,  and there confuse their language, that they may not understand one

another‘s speech.


Also I heard the voice of the Lord, saying, Whom shall I send, and who will go for us? (Isaiah 6:8)

The   above   references   are   a   striking   case   of   plural   and   singular interchanged,  suggesting plurality  in unity. In Genesis 18:1-17 we read “And he lift up his eyes and looked, and, lo, three men stood by him: and when

he saw them, he ran to meet them from the tent door, and bowed himself toward the ground… “

The above incident is a striking one and the language is too, that God should manifest himself in the form of three.

There are many other passages where God and his Word and the Spirit are brought together as co-causes of effects.  In Isaiah 63:8-10 we read, “For  He said, “Surely  they are My people, children who will not lie. “So He became their Saviour.  In all their affliction He was afflicted, and the Angel  of  His  presence  saved  them:  in  His  love  and  in  His  pity  He redeemed them; and He bore them, and carried them all the days of old. But they  rebelled,  and grieved  His  Holy Spirit:  so  He turned  Himself against them as an enemy, and He fought against them”.

Here we have the three speakers, the covenant God of Israel (v.8), the angel of the presence (v.9) and the Spirit ‘grieved’  by their rebellion (v.10). both the creative activity of God and his government are, at a later stage, associated with the Word personified as “Wisdom” where St. Paul said in his first epistle to the Corinthians

“Christ the power of God, and the wisdom of God.” (1 Corinthians 1:24). As this verse of St Paul is derived from these verses in Proverb:

The LORD possessed me in the beginning of his way, before his works of old. I was set up from everlasting,  from the beginning,  or ever the earth was. When there were no depths, I was brought forth; when there were no fountains  abounding   with  water.  Before  the  mountains  were  settled, before the hills was I brought  forth: While as yet he had not made the earth, nor the fields, nor the highest part of the dust of the world. When he prepared  the heavens,  I was there: when he set a compass  upon the face  of  the  depth:   When  he  established  the  clouds  above:  when  he strengthened  the fountains  of  the  deep:  When  he gave  to  the  sea  his decree, that the waters should not pass his commandment: when he appointed  the  foundations  of  the  earth:  Then  I  was  by  him,  as  one brought up with him: and I was daily his delight, rejoicing always before him;

As well as with the Spirit as the Dispenser of all blessings and the source of physical strength, courage, culture and government, as we learn from Exodus:

And  I  have  filled  him  with  the  spirit  of  God,   in  wisdom,  and  in understanding,  and in knowledge, and in all manner of workmanship.

And in Numbers  he added:  And the LORD came down in a cloud, and spake unto him, and took of the spirit that was upon him, and gave it unto the seventy elders: and it came to pass, that, when the spirit rested upon

them, they prophesied, and did not cease.

Also, in Judges he said “And the Spirit of the LORD came upon him, and he judged Israel, and went out to war: and the LORD delivered Chushanrishathaim king of Mesopotamia into his hand; and his hand prevailed against Chushanrishathaim.” (Judges 3:10)

The threefold  source revealed  in creation  becomes still more evident  in the unfolding of redemption. At an early stage there are the remarkable phenomena  connected  with  the  angel  of  the  Lord  who  receives  and accepts divine honour (Genesis 16:2-13) as in the story of Hagar and Ishmael. And also, in (Genesis 22:11-16) the story of Abraham’s  sacrifice on the mountaintop in the land of Moriah.

In other passages the angel of the Lord not only bears the divine  name, but also has divine dignity and power, dispenses divine deliverance, and accepts  homage  and  adoration  proper  only  to GOD.  The Messiah  has deity ascribed to him, even when he is regarded as a person distinct from God “Therefore  the Lord himself shall give you a sign; Behold, a virgin shall conceive,  and bear a son,  and shall call his name  Immanuel.”

(Isaiah 7:14)

And also in (Isaiah 9:6) “For unto us a child is born, unto us a son is given: and the government  shall be upon his shoulder:  and his name shall be called  Wonderful,  Counsellor,  The mighty God, The everlasting  Father, The Prince of Peace. “

And of the Son we hear King David in his Psalms “The LORD said to my Lord, Sit at My right hand, Till I make Your enemies Your footstool. (Psalm 110:1)

The Spirit of God is also given prominence in connection with revelation and  redemption,  and  is  assigned  his  office  in  the  equipment  of  the Messiah  for his work (Isaiah 11 :2) “And  the Spirit of the LORD shall rest upon him, the Spirit of wisdom and understanding,  the Spirit of counsel and might, the Spirit of knowledge and of the fear of the LORD;

And in (Isaiah 42: I) Behold!  My Servant,  whom I uphold; My Elect, One in whom My soul delights!  I have put My Spirit upon Him: He bring forth justice to the Gentiles.

And in (Isaiah 61:1) “The Spirit of the Lord GOD is upon Me; because the LORD has anointed  Me to preach good tidings to the poor; He has sent Me to heal the brokenhearted,  to proclaim liberty to the captives, and the opening of the prison to them that are bound;”

Thus the God who revealed himself objectively through the Angel­ Messenger  revealed himself subjectively  in and through the Spirit, the Dispenser of all blessings and gifts within the sphere of redemption. The threefold Aaronic blessing in (Numbers 6:24) must also be noted as the prototype of the New Testament apostolic  blessing.

“The LORD bless you, and keep you: The LORD make His face shine upon you, and be gracious unto you: The LORD lift up His countenance upon you, and give you peace.”

In the New Testament:

Every Old Testament incident yields some New Testament truth.

By way of contrast it must be remembered that the Old Testament was written  before  the revelation  of  the doctrine  of the Trinity was  clearly given, and the New Testament after it.  In the New Testament it was given particularly in the incarnation  of God the Son, and the outpouring  of the Holy Spirit.   But however dim the light in old dispensation; the Father, Son and Holy Spirit of the New Testament are the same as in the Old Testament.

Before the advent of Christ, the Holy Spirit came into the consciousness of God-fearing  men in a degree that was not known since the close of Malachi ‘s prophetic ministry, more especially John the Baptist.  He called for repentance toward God, faith in the coming Messiah, and spoke of baptism of the Holy Spirit, of which his baptism with water was a symbol (Matthew  3:11).

“ I indeed baptise you with water unto repentance,  but He who is coming after me is mightier than I, whose sandals  I am not worthy  to carry,  He will baptise you with the Holy Spirit and fire.”

So where do we find the epochs of Trinitarian revelation  in the New Testament?

1: The Annunciation: The agency of the Trinity in the incarnation was disclosed  to Mary in the angelic annunciation that the Holy Spirit  would come upon her, the power of the Most High would overshadow  her and the child born of her would be called the Son of God (Luke 1:35). Thus the Father and the Spirit were disclosed as operating in the incarnation of the Son.

And the angel answered and said to her, “The Holy Spirit will come upon you, and the power of the Highest will overshadow  you; therefore,  also, that Holy One who is to be born will be called the Son of God.”

2: In the baptism of Christ: Trinity can be clearly distinguished, the Son is  being  baptised,  the  Father  speaking   from  heaven,  and  the  Spirit descending  in the objective  symbol of a dove. “And Jesus, when he was baptised, went up straightway  out of the water: and, lo, the heavens were opened  unto him, and he saw the Spirit of God descending  like a dove, and lighting  upon him: And lo a voice from heaven,  saying,  This is my beloved Son, in whom I am well pleased.” (Matthew 3: 16-17)

3: The teaching of Jesus: the teaching of Jesus Christ is Trinitarian throughout.  He spoke of the Father who sent him. Of himself as the One who reveals  the Father,  and the Spirit  as the One by whom He and the Father work. We find many references  to the latter in (John 14:7-9). In this indicates  Christ  deity,  his  pre-existence   and  the  unity  of  the  three underlying characteristic  of the divine in one nature of God Almighty.

If you had known Me, you would have known My Father also: and from now on you have known Him, and have seen Him. Philip said to him, Lord, show us the Father, and it sufficient for us. Jesus said to him, Have I been with you so long, and yet you have not known Me, Philip? He who has seen Me has seen the Father, so how can you say, ‘Show us the Father? “ Do you not believe that I am in the Father, and the Father in Me? The words that I speak to you I do not speak on My own authority; but the Father who dwells in Me does the works.  Believe Me that I am in the Father and the Father in Me, or else believe Me for the sake of the works themselves”

And of the Holy Spirit He said, “If you love Me, keep My commandments. And I will pray the Father, and He will give you another Helper, that may abide with you forever.” (John 14:15-16)

The Helper here indicates to the Holy Spirit which was poured  upon the apostles on the day of Pentecost:  “Now  when the Day of Pentecost had fully  come, they  were  all  with one accord  in one  place,  And suddenly there  came a sound  from  heaven,  as of a rushing  mighty  wind,  and it filled the whole house where  they were sitting.    Then there appeared  to them divided tongues,  as of fire, and one sat upon each of them. And they were all filled with the Holy Spirit and began to speak with other tongues, as the Spirit gave them utterance.” (Acts 2:1-4)

4: The commission of the Risen Lord . Christ instructs his disciples to go into the whole world with his message and baptize them in the name of the  Father  and of the Son  and  of the Holy Spirit. It is significant the name “Baptism” is one  but within  the bounds  of the one name  there is three distinct persons.

The  Christian  Church  is founded  on  the  doctrine  of  the  Trinity.  This evident,  as said before, in the outpouring of the Spirit at Pentecost.  This outpouring  brought the personality of the Spirit into a greater prominence and at the same time shed light anew from the Spirit upon the Son,

Therefore, in the universal Church we find the apostolic benediction interpreting  the deeper  meaning  of  the  Trinity  in Christian  experience “The grace of our Lord Jesus Christ and the love of God the Father and the fellowship  of the Holy Spirit be with you all” (2 Corinthians 13:14)

The doctrine  of Trinity  in the Christian  Church  is understood  to refer to God to be ONE God in his essential  being, but that in his being there are three  Persons,  yet so  as  not  to form  separate  and  distinct  individuals. They  are  three  modes  or  forms  in  which  the  divine essence  exists.

‘Person’ is, however, an imperfect expression of the truth inasmuch as the term denotes  to us a separate  rational and  moral  individual.  But  in the being of God there are not three individuals, but three personal self­ distinctions  within  the ONE  divine  essence. Then  again, personality  in man   implies   independence  of  will,  actions   and   feelings   leading   to behaviour peculiar to the person.   This cannot be thought  of in connection with the Trinity. In the Trinity, each person is self-conscious and self­ directing, yet never acting independently or in opposition.

When we say that God is a Unity we mean that, though God is in himself a threefold  centre of  life,  his life is not split  into three. He is ONE  in essence, in personality  and in will. When we say that God is a Trinity in Unity, we mean that there is a unity in diversity,  and that the diversity manifests itself in persons, in characteristics  and in operations. In them there is perfect equality in nature, honour and dignity.

Fatherhood  belongs to the very essence of the first Person and it was so from all eternity.  It is personal property of God ‘from whom every family in heaven and on earth is named (Ephesians 3:15)

The Son is called the ‘only begotten’ to suggest uniqueness. Christ always claimed for himself a unique relationship  to God as Father. (John 5:19)

“For as the Father has life in Himself, so He has granted the Son to have life in himself’’

As in Genesis 18:2-17,  the story suggests the Trinity of the Godhead. Here we learn that the whole Trinity is interested and exercised in seeking to bless and save man.  “And  he lift up his eyes and looked, and, lo, three men stood by him: and when he saw them, he ran to meet them from the tent door, and bowed himself toward the ground…”

The Father loved, and sent His Son; the Son loved, and gave Himself up to the death to redeem; the Spirit loved, and came to make His abode in the believing   hearts. This threefold salvation is summed up in the benediction. “The grace of our Lord Jesus Christ and the love of God the Father  and the fellowship  of the  Holy Spirit  be with  you all”  (2 Corinthians 13:14)

The Spirit  is revealed as the One who alone knows the depths of God’s nature: For the Spirit searches everything,  even the depths  of God … no one comprehends the thoughts of God except the Spirit of God

(1 Corinthians 2:10).

This is saying that the Spirit is just God himself in the innermost essence of His being.

The  doctrine  of  Trinity  arose  as  the  spontaneous  expression   of  the Christian experience.   The early Christians, knew themselves to be reconciled  to  God  the  father,  and  that  the  reconciliation  was  and  is secured for them by atoning work of the Son, and that it was mediated to them as an experience  by the Holy Spirit.  Thus the Trinity was and still is a fact before it was a doctrine, but in order to preserve it in the creedal faith of the Church the doctrine had to be formulated.

It is true that Christianity speaks of the Father as the First Person, and of the Son as the Second Person, and of the Holy Spirit as the Third Person; but “first,” “second,” “third” here do not represent a time order-rather the order of necessary relationship.

From the above we learnt that God is Wise and Living.   Now, he who is wise  discerns  because  of  his  wisdom;  and  he who  is living  is  living because he has life.  This is the mystery of the Trinity, which Christians confess of that Adorable Nature, Mind, Wisdom and Life.   Three co­-essential properties in One, and One who is glorified in three properties. The Mind has called Father and Begetter, because He is the Cause of all, and  First.    The Son  has  called  Wisdom  and  Begotten, because  He is begotten of the Mind, and by Him everything was made and created.  The Life has called, the Holy Spirit and Proceeding, because there is no other Holy Spirit but He.  He who is Holy is unchangeable.   Thus, these three properties are consubstantial.

Therefore, the implications of the doctrine of Trinity are vitally important not only for Christian theology, but for Christian experience and life.