Introduction To The Trinity

A difficult but fundamental concept within Christianity, the Trinity is the belief that God is three separate persons but is still a single God.

The core belief

The doctrine of the Trinity is the Christian belief that: There is One God, who is Father, Son, and Holy Spirit.

Other ways of referring to the Trinity are the Triune God and the Three-in-One.

The Trinity is a controversial doctrine; many Christians admit they don’t understand it, while many more Christians don’t understand it but think they do.

In fact, although they’d be horrified to hear it, many Christians sometimes behave as if they believe in three Gods and at other times as if they believe in one.

Trinity Sunday, which falls on the first Sunday after Pentecost, is one of the few feasts in the Christian calendar that celebrate a doctrine rather than an event.

A fundamental doctrine

The doctrine of the Trinity is one of the most difficult ideas in Christianity, but it’s fundamental to Christians because it:

  • states what Christians believe God is like and who he is
  • plays a central part in Christians’ worship of an “unobjectifiable and incomprehensible God”
  • emphasises that God is very different from human beings
  • reflects the ways Christians believe God encounters them
  • is a central element of Christian identity
  • teaches Christians vital truths about relationship and community
  • reveals that God can be seen only as a spiritual experience whose mystery inspires awe and cannot be understood logically

Unpacking the doctrine

The idea that there is One God, who is Father, Son, and Holy Spirit means:

  • There is exactly one God
  • The Father is God
  • The Son is God
  • The Holy Spirit is God
  • The Father is not the Son
  • The Son is not the Holy Spirit
  • The Father is not the Holy Spirit

An alternate way of explaining it is:

  • There is exactly one God
  • There are three really distinct Persons – Father, Son, and Holy Spirit
  • Each of the Persons is God

Common mistakes

The Trinity is not

  • Three individuals who together make one God
  • Three Gods joined together
  • Three properties of God
trinity cross Christianity praying


The Bible and why Christians believe in the Trinity

The idea of the Trinity does not supersede monotheism; it interprets it, in the light of a specific set of revelatory events and experiences.

Keith Ward, Religion and Creation, 1996 

Christianity adopted this complicated idea of God because it was the only way they could make sense of One God in the context of the events and teaching of the Bible.

Encounters with God

Humanity met God in three different forms:

  • God the Father: revealed by the Old Testament to be Creator, Lord, Father and Judge.
  • God the Son: who had lived on earth amongst human beings
  • God the Holy Spirit: who filled them with new life and power

What the Bible taught

The Bible taught that Christians were to worship Father and Son and Holy Spirit. It also taught that Christians should only worship God. Finally, it taught that there was only one God:

  • We must worship only God
  • We must worship God the Father
  • We must worship God the Son
  • We must worship God the Holy Spirit
  • There is only one God

This seemed to put Christians in an impossible position from which they were rescued by the doctrine of the Trinity, which solved the puzzle by stating that God must be simultaneously both Three and One.

Scripture and the Trinity

For obvious reasons the Trinity is not referred to in the Old Testament, although many writers think that the Old Testament does drop heavy hints about it – for example when it uses a plural Hebrew noun to refer to God.

The New Testament of the Bible never explicitly refers to the Trinity as such, but it does contain a number of references to the Economic Trinity:

Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit.

The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all. (Matthew 28:19)

One text that is often quoted to provide scriptural authority for the doctrine of the Trinity is now thought to have been added to the text much later, and with the specific purpose of justifying the doctrine. (2 Corinthians 13:14)

For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost; and these three are one 

The mystery of the Trinity: (1+1+1=1) = Nonsense!

This idea that three persons add up to one individual seems like nonsense. And logically, it is.

So Christians don’t try to understand the doctrine of the Trinity logically or as a problem of arithmetic.

Unfortunately most other attempts to explain the Trinity don’t really capture the concept either, or are very difficult to understand.

God is not like us

One way out of the problem is to say that God is not like human beings and human beings get in a mess when they try to describe God using the same sort of language and understanding that they use to describe other human beings.

But human beings don’t have any other language available, so they have to do the best that they can with it. That’s fine, as long as they remember that the whole truth of the nature of God is simply beyond them.

So the doctrine of the Trinity only attempts to provide a rudimentary sketch of the mystery of God’s nature, rather than a full description of what God is like. God is a mystery, before which humanity should stand in awe.

Why the Trinity is important

Before trying to understand the doctrine of the Trinity, it’s vital to realise why it’s important.

Its purpose is not to provide factual knowledge of God’s hidden nature of the sort that describes a dog as “having 4 legs, fur, barks, bites, domesticated by humankind etc”.

The doctrine of the Trinity has other functions:

  • it brings humanity face to face with the mystery of God
  • it helps humanity recognise the God they meet in the Bible, in history and in their own lives
  • it helps humanity understand God’s complexity, otherness and mystery
  • it helps humanity worship God
  • it steers humanity away from wrong ideas of God, such as:
    • a patriarchal/hierarchical God
    • a God who can be logically understood
  • it is the foundation of much Christian worship and liturgy
  • it helps humanity understand its own nature as made in the image of God
  • it provides a model for human relationships, both as individuals and in community

So, for example, one might be inspired by the doctrine of the Trinity to come up with an understanding of human relationships that was something like this…

  • Human beings are made in the image of God
  • God is a community of persons in a mutual loving relationship
  • Therefore the essence of humanity is to be found in human relationships with others, with God, and with God’s creation
  • These relationships are filled with transforming power
  • For human beings to live truly in the image of God, these relationships must be mutual, generous and just
  • These relationships must acknowledge and value difference as well as sameness
  • These relationships must accept as well as give

That’s one way in which contemplating the Trinity might provide useful information for a Christian as to how they should try to live their life.

Making use of the Trinity

Is the Trinity a useful idea?

The Christian doctrine of the Trinity is not just an abstract belief, but something that has real practical use for those who believe it.

Absolutely nothing worthwhile for the practical life can be made out of the doctrine of the Trinity taken literally.

Immanuel Kant, Der Streit der Fakultäten

…the doctrine of the Trinity so easily appears to be an intellectual puzzle with no relevance to the faith of most Christians.

Karen Kilby

Until quite recently, many theologians thought that the doctrine of the Trinity was pretty pointless.

And the churches themselves disagree about the content of the doctrine; the most common Western statement of the Trinity is not accepted by the Eastern churches.

And yet somehow it remains at the heart of the Christian faith:

It is impossible to overemphasize the importance of the Christian doctrine that God is one in three persons. This has correctly been called the teaching distinctive of the Christian faith, that which sets the approach of Christians to the “fearful mystery” of the deity apart from all other approaches.

Gerald S. Sloyan, The Three Persons in One God, 1964 

The Trinity and Worship

Christian worship is inherently Trinitarian. Christians worship God in the presence of Christ and with the Holy Spirit within them.

So for example:

  • Worship and praise are offered “to God through Jesus Christ in the Holy Spirit”
  • Blessings are given “In the name of the Father and of the Son and of the Holy Spirit”, the sign of the Cross is a Trinitarian gesture.
  • The creed, the fundamental statement of Christian belief, sets out the Trinitarian nature of God.
  • Baptism is carried out “in the name of the Father, and of the Son, and of the Holy Spirit”.

Eucharistic prayers are firmly Trinitarian in concept. The traditional doxology is Trinitarian:

Glory be to the Father, and to the Son, and to the Holy Ghost;

As it was in the beginning, is now, and ever shall be,

World without end. Amen

Trinitarian doxology

Many hymns are explicitly Trinitarian, such as this one:

Holy, holy, holy! Lord God Almighty!
Early in the morning our song shall rise to thee;
Holy, holy, holy! Merciful and mighty,
God in three Persons, blessed Trinity!

Or this

I bind unto myself today
the strong name of the Trinity,
by invocation of the same,
the Three in One, and One in Three.

Or this

Firmly I believe and truly
God is Three, and God is One;
and I next acknowledge duly
manhood taken by the Son.

Or this modern classic

Shine, Jesus, shine,
fill this land with the Father’s glory;
blaze, Spirit, blaze,
set our hearts on fire. 

The Trinity as a lesson to Christians

The Trinity expresses the way Christians should relate to God:

  • worship God the Father
  • follow the example set by God the Son
  • God the Holy Spirit lives in them

The Trinity as a recipe for life

The doctrine of the Trinity teaches human beings how they should shape their lives.

Many Christians see the relationship between the persons of the Trinity as providing a recipe for the best sort of human relationships. These are relationships in which individuality is balanced with relationship; relationships whose basis is mutual love and perfect communication.

The relationship that exists within the Godhead is the basis for unity in every human relationship, be it marriage, family, or church.

Patrick Henry Reardon

The American theologian Catherine LaCugna suggested that the doctrine of the Trinity helps humanity answer the question

How are we to live and relate to others so as to be most Godlike?

Catherine LaCugna, God For Us: The Trinity and the Christian Life

She suggested that the Trinity taught:

a theology of relationship, which explores the mysteries of love, relationship, personhood and community within the framework of God’s self-revelation in the person of Christ and the activity of the Spirit.

Catherine LaCugna, God For Us: The Trinity and the Christian Life

And the key teaching within this doctrine of relationship is that the best relationships are those of equality and mutuality.

Social implications

The Trinity as a power structure

The relationships within God as a Trinity discredit any hierarchical power structure in which those lower down are dominated and oppressed by those above them.

Instead, using the example of the Trinity leads to an ideal structure of mutual interdependence and support in pursuit of a common aim.

Thus the Trinity shows the way God wants the world to be run and the power structures that he recommends to human society.

This seems to contradict the traditional idea of God as one Supreme Being, Lord of all, but should be seen as demonstrating the non-hierarchical nature of God in himself, without diminishing God’s status in relationship to others.

This idea can be developed in Church life:

  • in the hierarchical model power and authority in the church flow in one direction from God, through senior and junior clergy, down to the lay people
  • in the Trinitarian model there is a church of mutual self-giving and equality that emulates the community of the Trinity.
  • In this the members communicate with each other in a spirit of love that accepts responsibility for the well-being of each individual and that of the whole community.
  • In this way the Church, and each church and community become a unity in which diversity flourishes and in which differences are seen as valuable and essential elements in the substance of these institutions.

The Trinity and Liberation Theology

The liberation theologians thought it was essential to start thinking about the Trinity by focusing on its three-ness first, then its oneness.

They saw the Trinity as first and foremost a community of divine persons whose essence was in their shared existence, their shared relationship and their surrender to each other.

They objected to the hierarchical model of One God, because they thought that it justified political power structures that oppressed the poor and allowed the Church to continue with a patriarchal model that was out of date and unhelpful to the poor.

So the liberation theologians took the Trinitarian theology of relationships to a grand scale. They used it to promote the ideal human society as a closely related and unified group of equal people living so as to promote the good of society as a whole.

The leading liberation theologian Leonardo Boff said the Trinity was a “model for any, just, egalitarian (while respecting differences), social organisation.” It provided a “prototype of human community dreamed of by those who wish to improve society”. 

Essential and Economic Trinity

Some of the problems of the Trinity arise from confusion between the internal life and nature of the Trinity itself and the external life or “self-revelation” of God. The only thing humankind can directly know of God is his external life.

There are two ways of looking at God in Trinitarian terms:

  • The Essential (also called Immanent or Ontological) Trinity looks at the essence or substance of God; at what God is actually like in himself as he stands outside the created universe. It’s how God appears to God.
    • Warning: This is an unusual use of the word immanent, which Christians often use to refer to God’s actions in the world.
  • The Economic Trinity is concerned with humanity’s experience of God; in human lives, in creation, in salvation; and derives the nature of God from that experience. This is how God appears to humanity.
    • Some theologians point out that only the Son and the Spirit are directly met in the Economic Trinity.

The Economic and Essential Trinities are not two separate entities – just two ways of looking at God.

Are these two the same? Victor Shepherd (Professor of Systematic Theology at Tyndale University College, Toronto) put the question like this:

Is God’s revelation merely the “face” God wears as he turns to us, or is it who God is in himself?

Is his face something he merely displays, or does his face unambiguously disclose his heart?

Victor Shepherd

The Western Churches believe that they are pretty much the same and that human beings meet God fully and completely as he is through his actions.

The ‘economic’ Trinity is the ‘immanent’ Trinity and the ‘immanent’ Trinity is the ‘economic’ Trinity.

Karl Rahner, The Trinity, 1970

To put it another way: God’s actions reveal who God is. And since God acts as a threefold God, God himself must be threefold.

Some Western writers hint at the idea that there is no more to God than his actions in the world.

The Eastern Churches disagree, and teach there is much more to God than human experience can reveal.

Trinitarian heresies

Some theories of the Trinity are so wrong that they have been declared heretical.


The proponents of Modalism were Noetus and Praxeas (late 2nd century CE) and Sabellius (3rd century CE).

Modalism teaches that Father, the Son, and the Holy Spirit are not distinct personalities, but different modes of God’s self-revelation.

The idea is that there is only one God, but that this one God reveals himself in different ways and different forms – sometimes as Father, sometimes as Son, sometimes as Holy Spirit.

  • Father: The creator and the law giver
  • Son: The revealer, the Messiah and the redeemer
  • Holy Spirit: The sanctifier and giver of eternal life

One of the standard analogies for the Trinity is a good example of modalism: The Trinity is like water because water comes in three forms – ice, water, steam. This is Modalism because these are three states or modes of the substance water.

Some modalists believe that God revealed himself differently at different times in history, others believe that during any particular period of history God can reveal himself in different ways; so when God is acting as redeemer, that’s God the Son, and so on.

Warning: Some modern writers refer to the different persons of the Trinity as different “modes of being”, but they aren’t guilty of Modalism because they are not referring to different modes in which God appears to humanity, but different internal ways in which God is to him/herself.


Tritheism portrays Father, Son and Holy Spirit as three independent divine beings; three separate gods who are linked together in some special way – most commonly by sharing the “same substance” or being the same sort of thing.

People often make this mistake because they misunderstand the use of the word “persons” in defining the Trinity; it does not mean that Father, Son and Holy Spirit are three separate personalities.


This is the idea that Father, Son and Holy Spirit together make up God. This would suggest that each of the persons of the Trinity is only part God, only becoming fully God when they are together.


Monarchianism stresses God as One and downgrades the idea of the Trinity; it comes in various versions:


Christ was born human and adopted by God at his resurrection (or baptism).


This isn’t a strictly Trinitarian heresy but it’s relevant because it’s the idea that the Son is in some way less fully God than the Father.

The Filioque fracas

Can you believe that the Christian Church fell apart over a single word?

Well it’s true: The greatest row in the history of Christianity centred on a single word filioque and on the doctrine of the Trinity.

The row split the Eastern Church, which mostly became the Orthodox Church, and the Western Church, which became the Roman Catholic Church and its later Protestant offshoots. There were other matters at issue as well, but the row over “the filioque clause” led to the Great Schism of 1054.

What the row was about

The Churches were arguing about whether the Son played any part in the origin of the Spirit as one of the persons of the Trinity from the Father, who is the only ultimate source.

The Latin word filioque, which means “and from the son”, was gradually inserted by Western churches into the Nicene Creed so that it stated that the Holy Spirit proceeds not from the God the Father alone, as the early Church Fathers believed, but from both God the Father and God the Son.

The Eastern wing of the Church believed and believes that the Father alone had given rise to the Holy Spirit, and the idea that both Father and Son had done so was condemned as heretical.

Even today, the creed used by the Eastern Churches professes faith “in the Holy Spirit who proceeds from the Father,” without mentioning the Filioque. The Western Churches (i.e. the Roman Catholic and Protestant churches) expressly say that the Holy Spirit “proceeds from the Father and the Son.”

There were fundamental problems of authority as well as of doctrine. The Eastern wing of the Church was angry that the Western wing of the Church had altered a fundamental part of the creed without their agreement – indeed without even consulting them. This didn’t seem to them like the behaviour of a united church, and so the two wings eventually went their separate ways.

Many church historians think that the Western wing of the Church did behave very badly by trying to introduce such a major change to Christian belief in such a cavalier way.

The doctrine of ‘dual procession’

This is the name that theologians give to the idea that the Spirit proceeds from both Father and Son.


When Christians say that the Holy Spirit proceeds from the Father (and the Son), what do they mean, and why do they use such an odd word?

The word comes from the Greek text of John 15.26, which speaks of the one “who proceeds (ekporeuetai) from the Father”. The Greek word has the sense of movement out of, and early theologians used it to show that the Spirit’s origin was within the person of the Father.

Greek theologians restricted this Greek word to this particular technical use – the coming forth of the Spirit from the Father – so that it has a unique reference to the relationship of the Father and the Spirit.

The Greek theologians also thought that the way in which the Spirit comes from the Father is similar to, but significantly different from, the way the Son comes from the Father.

The equivalent Latin word is “procedure“, but unlike the Greek word it doesn’t include the notion of a starting point within something; it’s a more general word for movement. This different meaning may have contributed in a small way to the dispute.

Latin theologians taught that the Spirit comes from both the Father and the Son, but comes from each of them in significantly different ways. These differences do not diminish the Father’s role as the only cause of everything that exists.

The arguments

The arguments in the dispute are highly technical, and seem pretty dull to anyone except a theologian – but they stirred hugely passionate debates in the church because they were about something that mattered terribly: the nature of God.

To get a flavour of the passion the debate aroused, look at this comment from a 9th century Patriarch:

…dishonourable men emerged out of the darkness (that is, the West), and poured down like hail or, better, charged like wild boars upon the newly-planted vineyard of the Lord, destroying it with hoof and tusk, which is to say, by their shameful lives and corrupted dogmas.

Encyclical to the Eastern Patriarchs

Here are some of the arguments that were used by each side.

Against the filioque clause

  • The nature of God the Father is to be the sole cause of everything
  • God the Father is the “First Person of the Trinity” because he gives existence to everything else
  • Giving life to others is what it means to be a father, it is not what it means to be a son
  • Jesus said only that the Spirit proceeds from the Father

But when the Counsellor comes, whom I shall send to you from the Father, even the Spirit of truth, who proceeds from the Father, he will bear witness to me.

John 15:26

  • The idea that the Spirit proceeds from Father and Son detracts from the separate character of each person of the Trinity, and confuses their relationships
  • The idea that the Spirit proceeds from the Son as well as the Father diminishes the status of God the Father

In favour of the filioque clause:

  • Jesus did not say that the Spirit only proceeds from the Father
  • The Creed and the Bible say that the Son does give life to others:

All things were made through him, and without him was not anything made that was made.

John 1:3

  • Jesus said that the Spirit proceeds from both the Father and the Son:

Jesus said to them again, “Peace be unto you. As the Father has sent me, even so send I you.” And when he had said this, he breathed on them and said to them, “Receive the Holy Spirit”

John 20:21-3

  • If the Spirit and the Son both proceed only from the Father, then there is no internal distinction between them in the Godhead (as opposed to their action on Earth).
  • The Spirit is the bond of love that unites Father and Son – this bond must proceed from both Father and Son
  • The Spirit proceeds eternally from the Father and Son as from a single principle

Moving closer

In modern times the Eastern and Western churches have moved closer together.

In December 1965 Pope Paul VI and Patriarch Athenagoras of Constantinople revoked the excommunications of 1054 and called for an active pursuit of mutual understanding.

Glossary of the Trinity

Appropriation and Perichoresis are two ideas that are important in reconciling God’s one-ness with the three-ness of God in human experience.


Appropriation teaches that all three persons of the Trinity do everything God does, but that it is appropriate to see some actions as being particularly associated with one specific person of the Trinity.

So the Father is associated with creation and the Son with redemption, but all three persons are actually involved with these actions.


Perichoresis is a Greek word that means permeation without confusion.

This is the idea that each of the persons of the Trinity shares completely in the life of the other two.

Theologians say that each of the persons of the Trinity “interpenetrates” the others, so that the distinctions between the persons are preserved and the substance of God is not divided into three.

The theologian Leonardo Boff described perichoresis as “the intimate and perfect inhabitation of one Person in the other,” meaning that the three persons of the Trinity live in and relate to each other perfectly.

Many modern writers prefer to use the word indwelling to express the idea of perichoresis. They say there is a mutual indwelling of the persons of the Trinity.

Other words for the same thing are coinherence and circuminsessio.

All facets of divine activity are reflected in all three persons of the Trinity. They are dynamically intermingled. They may not be separated.

Richard B. Hays


Persons is a theological word that answers the question “Three what?”

The traditional statement of the doctrine of the Trinity is this: There are three persons within the Godhead; Father, Son and Holy Spirit. These three persons have equal status and are equally divine.

But the word person in this definition doesn’t mean person in any sense that modern people understand it – it’s an ancient technical philosophical term, which originally meant the mask worn by actors playing parts in an ancient Greek play.

The Greek word was hypostases (the singular term is hypostasis). The ancient writers said that there were three distinct hypostases in one ousia (ousia is the word now translated as substance – see below.)

There’s a hint here of a very important concept in the idea of the Trinity. Actors playing a part in a play do so in relationship to other members of the cast, and a key element of the doctrine of the Trinity is that the three persons of the Trinity are in relationship with one another.

But “person” to modern people means, at the very least, a separate centre of consciousness, and more usually, an individual human being. That is not what it means in the definition of the Trinity.

The idea that the three persons of the Trinity are separate individuals is the heresy of tritheism.

Unfortunately, modern theological translations of the word “persons” into phrases such as “distinct manners of subsisting” don’t make things much clearer (and that particular phrase, as it happens, sounds very like the heresy of modalism).


This word is used to describe the coming forth of one of the persons of the Trinity from another (or from both the others).

The use of this word in statements of the Trinity is a reminder that there is movement and dynamic energy in the Christian concept of God.


Substance is the theological word that answers the question “One what?”

It comes from the Greek word ousia, which means “beingness”, but it has a more restricted meaning in this context than it had had to the ancient Greek philosophers who coined the word.

A substance is a thing which fully exists; a presence in the universe – so for example, a dog is a substance. Although in the case of God this is not a substance made of matter.

The key concept of substance is that of unity – it’s not separate from the three persons of the Trinity, it’s what makes them one.

This page is borrowed and adapted from BBC

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