The doctrine of the Trinity is uniquely about the God of the Bible. It is about God’s revelation to us regarding His simultaneous oneness and threeness, His relation with His creation, and His work of redemption. It is the doctrine that undergirds all other doctrines. It is the mystery of God revealed not only in history, but also in and through the Scriptures that faithfully record those historical events.1 Those events being, the Father sending the Son and the Father and Son sending the Holy Spirit for the application of our salvation (John 17:25 – 26; Gal 4:4 – 7; Eph 1:3 – 14). The Trinity is not merely some abstract doctrine to be pondered or debated upon, but about the God who is to be experienced. The Triune God is all together beautiful, good, holy, just, loving, and powerful. In addition, the Trinity is what makes Christianity unique and distinguished from Judaism, Islam, and other world religions.2

How is the Trinity practical or relevant? This question is one I have heard constantly from well-meaning Christians. They follow by saying something like, “We need a practical theology, not something intellectual or speculative.” What does this line of questioning reveal about their presuppositions?

I see four major presupposed beliefs. First, their understanding of the doctrine of the Trinity is devoid of any practical use. Second, they do not believe the Trinity is an essential Christian doctrine. Third, their belief may very well be tethered to pragmatism, in which the doctrine’s value is determined by its usefulness or practicality.3 Lastly, they are not acquainted with the doctrine and its implications.  

At this juncture, I submit that the question, “How is the Trinity practical or relevant?” is the wrong query. Rather, what needs to be asked is “What are the implications of the doctrine of the Trinity for the Christian walk4 and for the life of the Church?”

The above sentiment may be a residue from the 20th century engagement with the doctrine.5 During such time, two charges arose from Classical Liberalism against the doctrine of the Trinity. The first charge came from the German historian, Adolf Von Harnack, who alleged that Greek philosophical speculations6 had infiltrated Christian theology and that the early church Fathers had uncritically absorbed Greek philosophy into Christian theology.7 Yes, Greek metaphysical language was very much used. However, it did not alter any Christian doctrine but was employed in the service of the Word of God.8 The second charge came from the German theologian, Friedrich Schleiermacher, who said that the doctrine of the Trinity was not an essential Christian doctrine. 9 As a result, he placed the Trinity as the last chapter of his book, The Christian Faith.

Contrary to Harnack and Schleiermacher, “The mystery of the Holy Trinity is ‘the Substance of the New Testament.’ The Trinity is not one topic of reflection among others, but rather constitutes the heart of the Christian faith.”10 In like manner, Augustine of Hippo regarded the Trinity as vitally important – “In no other subject is error more dangerous, or inquiry more laborious, or the discovery of truth more profitable.”11 To get this wrong means further distance from the truth. But to get this right is to have communion with the one true God.

There are many places to begin our journey into the doctrine of the Trinity. In what follows, I seek to answer these two questions: 1) What is the doctrine of the Trinity?, and 2) Why is the doctrine of the Trinity important for the Church?

What is the doctrine of the Trinity?

Fred Sanders observes, “the Trinity is the Christian Doctrine of God.”12 The Trinity tells us how Scripture reveals who God is. He is the one eternal self-existent God who is simultaneously the Father, Son and Holy Spirit. Conversely, The Father, Son and Holy Spirit are three eternal and distinct persons who equally share one infinite and undivided self-existent nature.

The Second Council of Constantinople of 553, also known as the 5th Ecumenical Council, captures it well:

If anyone will not confess that the Father, Son and Holy Spirit have one nature (phusis, natura) or substance (ousia, substantia), that they have one power (dunamis, virtus) and one authority (exousian, potestas), that there is a consubstantial (homoousios, consubstantialis) Trinity, one Deity to be adored in three hypostases (hupostaseis, subsistentiae) or persons (prosopa, personae): let him be anathema. For there is only one God and Father, from whom all things come, and one Lord, Jesus Christ, through whom all things are, and one Holy Spirit, in whom all things are.13

While this passage is replete with technical terms, they are nevertheless essential to understanding the nature of God and what is at stake. First, the Father, Son and Spirit share one divine nature. Second, because they share one divine nature, they also partake in the power and authority belonging to the divine nature. And third, this God is adored as one God in three persons. The term hypostases was used by the Cappadocian Fathers to signify the manner by which the three Persons relate to one another. The Father is unbegotten, the Son is begotten of God (not created), and the Spirit proceeds from the Father, who is not begotten.    

Additionally, this definition contains an anathema. It helps us understand that there are boundaries in place to safeguard not only the Scriptures but also believers. During a time of Trinitarian controversies and heresies, it was necessary to affirm a statement that demonstrates alignment with the universal church’s position. If an individual does not confess the Triune nature of God, that person is accursed and in danger of excommunication from communion with the church and God Himself. They took definitions and doctrine seriously.

Why is the doctrine of the Trinity important for the Church?

As has been alluded by Augustine and the 5th Ecumenical Council, these trinitarian matters are not to be taken lightly. The Athanasian Creed likewise contains a warning to its readers, stating, “Whoever wants to be saved should think thus about the Trinity.”  Simply put, if one does not worship the triune God then one is worshiping the wrong God. This assertion becomes all the more evident when people allege that Jews, Christians and Muslims worship the same God. The fact that Christians worship Jesus as God points to the reality of the Trinity. Jews consider this belief as blasphemy. Muslims consider it as a violation of the doctrine of Tawhid (the unitarian oneness of Allah), which incidentally is to also commit shirk (the sin of idolatry and or polytheism), the unpardonable sin that sends you to hell.14

Essentially, if God were not triune, we could not be saved. The Trinity’s importance is explained by the Father sending the Son, the second Person of the Trinity to assume a human nature, to become one of us. Consequently, after the resurrection, the Father and the Son sent the Holy Spirit to apply this great salvation so that we might become what He is by grace, namely sons of God. Since God is Father, Son and Holy Spirit, we can therefore be adopted as sons (Gal 4:4 – 6).

Moreover, since God is Triune, we get a glimpse into the life of the Trinity (eternal procession) and the pattern for missions (temporal missions). The Father, Son, and Holy Spirit have been in an eternal relation with one another. The life of the Trinity is marked by the processions, that is, the Father eternally begets the Son and eternally spirates the Spirit. Keep in mind that there never was a time when the Father was not the Father and the Son was not the Son and the Holy Spirit was not the Spirit. They have eternally existed in relation to one another. These processions are eternally occurring. Hence, when we read that the Son was begotten, it points to the relation of origin, namely the way the Father (paternity), Son (sonship) relate to one another. This is completely different to human begetting. Humans begin to exist at a point in time when they are begotten. On the contrary, when God begets the Son, the Son never really begins to exist because He is God the Son and has always existed. The eternal processions are then manifested in the temporal missions when the Father sends the Son and the Spirit into the world. Fred Sanders said, “Their coming into our history is an extension of who they have always been in a very specific, Trinitarian Way.”15 How do the temporal missions provide us with a pattern for missions?

Missions are about sending out for the purpose of blessing others with the Gospel. The Gospel of John provides us with a scene about the temporal missions. Jesus tells the disciples that in the same way that the Father sent Him, He sends them. Jesus proceeds to breathe on them by telling them, “Receive the Spirit” (John 20:21). Jesus follows the pattern of the eternal processions (the internal life of the Trinity) and the temporal missions (the sending of the Son and Spirit) when He sends His disciples. The temporal missions is further expanded with the Great Commission by sending out His disciples and telling them to baptize people in the singular name of the Father, Son and Holy Spirit (Matt 28:18-20). The Great Commission not only gives us a glimpse of the pattern for missions, but also the simultaneous distinction of the three Persons and their essential oneness by sharing the divine name — Yahweh.


Contrary to Harnack and Schleiermacher, the Trinity is saturated in the Scriptures and forms the basis of all other essential Christian doctrines. God revealed Himself as one in Being and three in Persons, not only in history, but in His Holy Scriptures. The Father, Son and Holy Spirit are three eternal and distinct persons who equally share one infinite and undivided self-existent nature. If God is not Triune, we cannot be saved. If God is not Triune, we cannot be adopted as sons and we won’t have a model for missions. The Trinity makes the Christian faith unique. Therefore, the doctrine of the Trinity is practical because it is essential.

1 By the historical events I am referring to the events as they unfold in history, but also how they are progressive revealed and communicated in Scripture. Hence, Jesus’ incarnation and the Spirit’s procession are historical events, but they occurred at the fullness of time and likewise they are recorded special revelation as found in the Holy Scriptures. 

2 The three monotheistic faiths are Judaism, Christianity, and Islam. But what differentiates them is that Christianity alone affirms a Trinitarian-monotheism. Judaism and Islam are strictly unitarian-monotheism and hence reject the Christian understanding of God as being one in essence and three in Persons.  

3 There are generally three worldview historical presuppositions. They are Premodernity, Modernity, and Postmodernity. The Premodern hermeneutic operates on trust and faith and their test for truth is the correspondence theory of truth. The Modern hermeneutic operates on doubt and their test for truth is the coherence theory of truth. The Postmodern hermeneutic operates on suspicion and their test for truth is the pragmatic test of truth. For more detailed information on the above see Craig V. Mitchell, Charts of Philosophy and Philosophers. Zondervan Charts (Grand Rapids, MI: Zondervan, 2007).

4 Nicky Cruz, former New York Street gangster, seems to think that it is more than mere speculation. As a new believer Cruz said this about the Trinity. “Something has emerged in my walk with God that has become the most important element of my discipleship. It has become the thing that sustains me, that feeds me, that keeps me steady when I am shaky. I have come to see God, to know Him, to relate to Him as Three-in-one, God as Trinity, God as Father, Saviour, and Holy Spirit. God has given me over the years a vision of Himself as Three-in-one, and the ability to relate to God in that way is the single most important fact of my Christian growth.” Nicky Cruz with Charles Paul Conn, The Magnificent Three (Old Tappan, NJ: Revell, 1976). For easier access to an elaboration on Nicky’s thoughts on the Trinity also see The Trinitarian Theology of Nicky Cruz – The Scriptorium Daily.

5 See Stephen R. Holmes, The Quest For the Trinity: The Doctrine of God in Scripture, History and Modernity (Downers Grove: IVP Academic, 2012).  

6 These great doctrines were not arrived at by mere speculation or as a result of Greek pagan philosophes, but in the throes of opposition and heretical ideas confronting the truth about the nature of Christ and of God. These doctrines arise from the Scriptures. The early church Fathers argued that not only were the doctrines of the Trinity and the Incarnation Scriptural, but they were prescribed by Scripture. See the following for accurate historical development of the doctrines of the Trinity and Incarnation. Louis Berkhof, The History of Christian Doctrines (London: The Banner of Truth, 1937); Earle E. Cairns, Christianity Through the Centuries: A History of the Christian Church. 3rd Edition (Grand Rapids, MI: Zondervan, 1996); John Behr, The Way to Nicea Vol. 1 (Crestwood, NY: St Vladimir’s Seminary Press, 2001); John Behr, The Nicene Faith Vol. 2 Part 1 & 2 (Crestwood, NY: St Vladimir’s Seminary Press, 2004).  

7 Adolf Von Harnack, The History of Dogma (New York: Russell & Russell, 1958), 1, 17.           

8 Those who opposed orthodoxy used the same scriptural language equivocally, thus making it appear that they espoused the same beliefs concerning Jesus’ nature and the Triune nature of God. One example is the term begotten. For Arius it meant that Jesus was created, but for Athanasius it did not mean created, rather he used it because it was biblical language. He understood that for God to have a Son the Son would have to be of the same ousia (essence or substance) of the Father. This then made the use of metaphysical language and terms essential to distinguish the nuances inherent in the biblical text. A modern-day example is that of Mormon theology. Mormonism employs the same terms (Fall, salvation, eternal life, the Holy Spirit, the atonement, etc.) protestant evangelical Christianity do, but their meanings are diametrically opposed.

9 Friedrich Schleiermacher, The Christian Faith (Edinburgh: T. & T. CLARK, 1928), 738-751.

10 Gilles Emery, O.P. The Trinity: An Introduction to Catholic Doctrine on the Triune God (Washington, D.C.: The Catholic University of American Press, 2011), xi.

11 On the Holy Trinity, trans. A. W. Haddon, revised and annotated by W. G. T. Shedd: The Works of St Augustine, Nicene and Post Nicene Fathers, ed. Philip Schaff (reprinted Grand Rapids: Eerdmans, 1978), III.19.

12 Fred Sanders, “What is the Trinity? February 2, 2021,

13 Council of Constantinople II, Anathema 1 (Decrees of the Ecumenical Councils, 1:114).

14 For a treatment by a former Muslim who converted to Christianity see “Part two: Tawhid or the Trinity? Two Different Gods” in Nabeel Qureshi, No God But One Allah or Jesus?: A former Muslim Investigates the Evidence for Islam & Christianity (Grand Rapids, MI: Zondervan, 2016), 49-74.

15 Fred Sanders, The Deep Things of God: How the Trinity Changes Everything (Wheaton, IL: Crossway, 2010), 154.

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