The Triune God I: Doctrinal Foundations

The doctrine of the Trinity is one of the most foundational doctrines of the Christian Faith. Let us now see the foundational points of this doctrine and an overview of some of its critical points.

The Baptist Catechism asks this important question:

BLC Q. 11: Is there more than one God?

A: There is but one only: the living and true God. Yet, there are three persons in the Godhead: the Father, the Son, and the Holy Ghost. These three are one true, eternal God, the same in substance, equal in power and glory; although distinguished by their personal properties.

James White defines the Trinity as, “Within the one Being that is God, there exists eternally three coequal and coeternal persons, namely, the Father, the Son, and the Holy Spirit.”

(Latin: TRINITAS “three in one”)

  • There is ONLY ONE true God
  • There are three distinct persons
  • These three persons are co-equal and co-eternal.

These are the foundational points of the doctrine of the Trinity. To deny any of these is to worship an idol.

  • A denial of Monotheism leads to Tritheism (three gods).
  • A denial of the distinction of persons leads to Sabellianism (modalism – only one person in 3 different modes).
  • A denial of the equality and eternality of each person leads to subordinationism (the Son and the Spirit have lesser authority, and are not co-eternal and co-equal with the Father).
Arian Subordinationism - The subordination of Christ to God according to the economy implied subordination at the level of God’s being.

In this divine and infinite Being there are three subsistences, the Father, the Word or Son, and Holy Spirit,27 of one substance, power, and eternity, each having the whole divine essence, yet the essence undivided:28 the Father is of none, neither begotten nor proceeding; the Son is eternally begotten of the Father;29 the Holy Spirit proceeding from the Father and the Son;30 all infinite, without beginning, therefore but one God, who is not to be divided in nature and being, but distinguished by several peculiar relative properties and personal relations; which doctrine of the Trinity is the foundation of all our communion with God, and comfortable dependence on Him. 1689 2.3

Each person of the Trinity, when considered in himself, is absolutely, one hundred percent God, and at the same time one hundred percent of God is in each person. The whole God is in each person, and each person is the whole God.

Robert Letham

Historically, theologians distinguish between IMMANENT (theology/theologia) and ECONOMIC (Economy/oikonomia). The former refers to God as he is in himself apart from history (ad intra/in se), or the Triune God inwardly. The latter refers to God’s revelation of Himself in the incarnate Christ (ad extra) or “God for us” and the Triune God outwardly.


Triadic Passages

Eph 2:18 …For through Him we both have our access in one Spirit to the Father.

John 15:26 when the Helper comes, whom I will send to you from the Father, namely, the Spirit of truth who comes from the Father, He will testify about Me.

Mt. 28:19 Go, therefore, and make disciples of all the nations, baptizing them in the Name of the Father and the Son and the Holy Spirit 2 Cor 13:14  The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all.

From these passages, we can clearly see the three persons: The Father, the Son, and the Holy Spirit. Observe the basic distinction between the three persons below (more on this on our next blogs):

  • The Father – paternity (“unbegottenness,” active generation, and active spiration);
  • The Son – filiation or sonship, passive generation, active spiration;
  • The Holy Spirit – procession or passive inspiration. 

Paternity, filiation, and procession, so far from being accidental properties of the divine being, are the eternal modes of existence of, and the eternal immanent relations within, that being.

Herman Bavinck

Absolute Monotheism: Old Testament

De 6:4“Hear, O Israel: The LORD our God, the LORD is one.” 

De 4:35 To you it was shown, that you might know that the LORD is God; there is no other besides Him. 

Isa 43:10 “You are My witnesses,” declares the LORD, “and My servant whom I have chosen, in order that you may know and believe Me and understand that I am He. Before Me there was no God formed, and there will be none after Me”

Absolute Monotheism: New Testament

Mk 12:29 – Jesus answered, “The most important is, ‘Hear, O Israel: The Lord our God, the Lord is one.

Jas 2:19 – yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist

Rom 3:30 – since God is one —who will justify the circumcised by faith and the uncircumcised through faith. 

Those who say that Trinitarianism is Tritheism do not understand the biblical doctrine of the Trinity. Both the Old and New Testaments affirm that God is One. But again, this is not a denial of the Trinity. One has to prove that the One God is also one person, which the Scriptures know nothing about.

The Simplicity of God

It is also important to understand the Triune God in light of God’s simplicity.

All that is in God is God. According to Dolezal in his book All that is in God, there was no composition in the one substance or nature of God and in particular, God and his attributes are one and the same. 

  • It safeguards that idea that the three persons are not one-third God.
  • It excludes the idea that there “were degrees of divine existence,”
  • It affirms that the divine persons were one in being, work/function, and authority.

The mind of man cannot fully understand the mystery of the Trinity. He who has tried to understand the mystery fully will lose his mind; but he who would deny the Trinity will lose his soul.

Harold Lindsell and Charles J. Woodbridge,

Thus the question comes to this: whether the mystery of the Trinity is a fundamental article, necessary to the faith of all believers, so that not only the denial, but even the ignorance of it cannot consist with salvation. This the adversaries deny; we affirm (influenced principally by the following arguments). – Francis Turretin (Institutes of Elenctic Theology Volume 1. 3rd topic, 24th question)

To God be the glory!

1 According to Francis Turretin, Hence the word “subsistence” (called by the Greeks hyparxis) marks a mode of subsisting (tropos hyparxeōs) or personality. Now to subsist differs from to exist. To exist means that a thing actually is without its causes in the nature of things, which applies to accidents no less than to substances; but to subsist means a mode of existing proper to substances (Institutes of Elenctic Theology Volume 1. 3rd topic, 23rd question)


  • White, J. R. (1998). The forgotten Trinity. Bethany House Publishers.
  • H Bavinck, Bolt, J., & Vriend, J. (2004). Reformed dogmatics / 2, God and Creation / Herman Bavinck ; John Bolt, general ed. ; John Vriend, transl. [from the Dutch]. Baker Academic, Cop.‌
  • Beeke, J. R., & Jones, M. (2012). A Puritan theology : doctrine for life. Reformation Heritage Books.
  • Ames, W. (1958). Selections from the Marrow of Sacred Divinity, drawne out of the Holy Scriptures and the interpreters thereof, and brought into method.‌
  • Letham, R. (2019). The Holy Trinity : in scripture, history, theology, and worship. P&R Publishing.
  • Franciscus Turrettinus, Turretin, F., George Musgrave Giger, & Dennison, J. T. (1992). Institutes of elenctic theology. P&R Publications [= Presbyterian And Reformed Publishing Company.
  • Sproul, R. C. (2019). What Is The Trinity?
  • Dolezal, J. E. (2017). All that is in God : evangelical theology and the challenge of classical Christian theism. Reformation Heritage Books.

Published by Jeff Chavez

Sinner saved by grace

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