The Trinity:

Definition of Terms:

  • Trinity:  the belief in one God who exists as three distinct persons: the Father, the Son (Jesus Christ), and the Holy Spirit. These three persons are understood to be co-eternal, co-equal, and consubstantial, meaning they share the same divine essence.
  •  Consubstantial:  a term used to describe the Trinity of the Father, Son (Jesus Christ), and Holy Spirit are of the same substance or essence. It signifies that they share a fundamental unity of being, possessing the same divine nature. The term “consubstantial” emphasizes the essential oneness and equality of the three persons within the Godhead, affirming that they are not separate entities but inseparably united in their divine essence.

The Trinity refers to the Christian doctrine that within the Godhead, there are three distinct Persons: the Father, the Son (Jesus Christ), and the Holy Spirit. These three Persons are considered to be co-eternal, co-equal, and consubstantial, meaning they share the same divine essence or nature. The Trinity teaches that while there is one God, this one God exists in three Persons who are intimately connected and yet distinct from one another.

While the term “Trinity” is not explicitly mentioned in the Bible, the theological concept of the Triune God can be inferred implicitly from Scripture. The Gospel of Matthew 28:19 indicates that the Father, Son, and Holy Spirit are distinct entities yet share a common divine nature: “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”. Paul, in 2 Corinthians 13:14, highlights the presence and involvement of all three Persons of the Trinity in the lives of believers: “The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all.” Jesus Himself implies that He and the Father are distinct from the Holy Spirit: “And I will ask the Father, and he will give you another Helper, to be with you forever” (John 14:16). Implicit references to the Trinity can also be found in the Old Testament, such as Genesis 1:26.

The early Church understood the Trinity as a foundational doctrine, although the explicit language and terminology used to describe it continued to develop over time. Church Fathers played a crucial role in articulating and defending this understanding. They contributed to the early Church’s understanding of the Trinity through their writings, sermons, and theological debates.

Theophilus of Antioch is one of the earliest known Fathers to use the term “Trinity” in 180 A.D. Tertullian (c. 160-220 AD) would soon after coin the term “Trinity” (Latin: trinitas). Tertullian wrote extensively on the nature of God, defending the Trinity against heretical views such as Modalism. Athanasius (c. 296-373 AD), a staunch defender of the Trinity against the Arian heresy, affirmed the full divinity of the Son, emphasizing the concept of “homoousios” (of the same substance) in relation to the Father. Basil the Great (c. 329-379 AD), along with his brother Gregory of Nyssa and their friend Gregory of Nazianzus (known as the Cappadocian Fathers), highlighted the role of the Holy Spirit in the life of believers. Augustine of Hippo (354-430 AD), one of the most influential theologians in Western Christianity, made significant contributions to the understanding of the Trinity in his work “De Trinitate” (On the Trinity) where he explored the analogy of the human mind as a reflection of the Triune nature of God.

The insights and arguments of the Church Fathers played a vital role in formulating the foundational principles of the Trinity, providing a framework for subsequent theological developments. Their insights helped form the basis for early Church Councils to authoritatively define the nature of the Godhead. The Church Councils played a significant role in defining and clarifying the doctrine of the Trinity.

  1. Council of Nicaea (325 AD): This council was convened to address the teachings of Arius, who denied the full divinity of Jesus Christ. The Council affirmed the divinity of Christ and formulated the Nicene Creed, which explicitly declared the Son to be “of one substance (consubstantial) with the Father.” This emphasized the eternal and uncreated nature of Christ and His equality with the Father.
  2. Council of Constantinople (381 AD): Building upon the work of the Council of Nicaea, this council further clarified and expanded the understanding of the Trinity. It affirmed the divinity of the Holy Spirit and established the Holy Spirit as the third Person of the Trinity. The Nicene-Constantinopolitan Creed, also known as the Nicene Creed, was formulated during this council, reaffirming the beliefs of Nicaea and solidifying the Trinitarian doctrine.
  3. Council of Ephesus (431 AD): While the primary focus of this council was on the nature of Christ, it also had implications for the understanding of the Trinity. The council affirmed the unity of Christ’s person, asserting that the divine and human natures of Christ are inseparably united in one person. This reinforced the understanding of the Trinity as three distinct Persons within the one Godhead.
  4. Council of Chalcedon (451 AD): Similar to the Council of Ephesus, this council primarily addressed the nature of Christ but also contributed to the understanding of the Trinity. It affirmed the distinction between the divine and human natures of Christ while maintaining their perfect union in one person. This council’s teachings emphasized the co-equality and co-existence of the three Persons of the Trinity.

These Church Councils provided a platform for bishops and theologians to gather, discuss, and debate theological matters. Through careful examination of Scripture, theological reasoning, and the guidance of the Holy Spirit, these councils formulated creeds, statements, and definitions that helped shape the understanding of the Trinity within the Christian tradition. The decisions and formulations of these councils played a vital role in combating heresies, preserving orthodoxy, and establishing the doctrinal foundations of the Trinity.

Early Christians defended the concept of the Trinity against several heresies, such as Arianism, Nestorianism, Monophysitism, and Monothelitism. One such heresy was Modalism, which claimed there is only one person in the Godhead, with the Father, Son, and Holy Spirit being different “modes” of that one person. Modalism has recently resurfaced in the twentieth century through the Oneness Pentecostal movement.

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Bible Verses:

Matthew 28:19:

“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.”

2 Corinthians 13:14:
“The grace of the Lord Jesus Christ, the love of God, and the communion of the Holy Spirit be with all of you.”

Hebrews 9:14:
“how much more will the blood of Christ, who through the eternal Spirit offered himself without blemish to God, purify our conscience from dead works to worship the living God!”

John 14:16:
“And I will ask the Father, and he will give you another Advocate, to be with you forever.”

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Church Father Quotes:

The Didache

“After the foregoing instructions, baptize in the name of the Father, and of the Son, and of the Holy Spirit, in living [running] water. . . . If you have neither, pour water three times on the head, in the name of the Father, and of the Son, and of the Holy Spirit” (Didache 7:1 [A.D. 70]).

Ignatius of Antioch

“[T]o the Church at Ephesus in Asia . . . chosen through true suffering by the will of the Father in Jesus Christ our God” (Letter to the Ephesians 1 [A.D. 110]).

“For our God, Jesus Christ, was conceived by Mary in accord with God’s plan: of the seed of David, it is true, but also of the Holy Spirit” (ibid., 18:2).

Justin Martyr

“We will prove that we worship him reasonably; for we have learned that he is the Son of the true God himself, that he holds a second place, and the Spirit of prophecy a third. For this they accuse us of madness, saying that we attribute to a crucified man a place second to the unchangeable and eternal God, the Creator of all things; but they are ignorant of the mystery which lies therein” (First Apology 13:5–6 [A.D. 151]).

Theophilus of Antioch

“It is the attribute of God, of the most high and almighty and of the living God, not only to be everywhere, but also to see and hear all; for he can in no way be contained in a place. . . . The three days before the luminaries were created are types of the Trinity: God, his Word, and his Wisdom” (To Autolycus 2:15 [A.D. 181]).

Irenaeus of Lyons 

“For the Church, although dispersed throughout the whole world even to the ends of the earth, has received from the apostles and from their disciples the faith in one God, the Father Almighty . . . and in one Jesus Christ, the Son of God, who became flesh for our salvation; and in the Holy Spirit” (Against Heresies 1:10:1 [A.D. 189]).

Tertullian of Carthage 

“We do indeed believe that there is only one God, but we believe that under this dispensation, or, as we say, oikonomia, there is also a Son of this one only God, his Word, who proceeded from him and through whom all things were made and without whom nothing was made. . . . We believe he was sent down by the Father, in accord with his own promise, the Holy Spirit, the Paraclete, the sanctifier of the faith of those who believe in the Father and the Son, and in the Holy Spirit” (Against Praxeas 2 [A.D. 216]).

“And at the same time the mystery of the oikonomia is safeguarded, for the unity is distributed in a Trinity. Placed in order, the three are the Father, Son, and Spirit. They are three, however, not in condition, but in degree; not in being, but in form; not in power, but in kind; of one being, however, and one condition and one power, because he is one God of whom degrees and forms and kinds are taken into account in the name of the Father, and of the Son, and of the Holy Spirit” (ibid.).

“Keep always in mind the rule of faith which I profess and by which I bear witness that the Father and the Son and the Spirit are inseparable from each other, and then you will understand what is meant by it. Observe now that I say the Father is other [distinct], the Son is other, and the Spirit is other. This statement is wrongly understood by every uneducated or perversely disposed individual, as if it meant diversity and implied by that diversity a separation of Father, Son, and Holy Spirit” (ibid., 9).

“Thus the connection of the Father in the Son, and of the Son in the Paraclete, produces three coherent persons, who are yet distinct one from another. These three are, one essence, not one person, as it is said, ‘I and my Father are one’ [John 10:30], in respect of unity of being not singularity of number” (ibid., 25).

Origen of Alexandria 

“For we do not hold that which the heretics imagine: that some part of the being of God was converted into the Son, or that the Son was procreated by the Father from non-existent substances, that is, from a being outside himself, so that there was a time when he [the Son] did not exist” (The Fundamental Doctrines 4:4:1 [A.D. 225]).

“For it is the Trinity alone which exceeds every sense in which not only temporal but even eternal may be understood. It is all other things, indeed, which are outside the Trinity, which are to be measured by time and ages” (ibid.).

Hippolytus of Rome 

“The Word alone of this God is from God himself, wherefore also the Word is God, being the being of God” (Refutation of All Heresies 10:29 [A.D. 228]).

Pope Dionysius

“Next, then, I may properly turn to those who divide and cut apart and destroy the most sacred proclamation of the Church of God, making of it [the Trinity], as it were, three powers, distinct substances, and three godheads. . . . [Some heretics] proclaim that there are in some way three gods, when they divide the sacred unity into three substances foreign to each other and completely separate” (Letter to Dionysius of Alexandria 1 [A.D. 262]).

“Therefore, the divine Trinity must be gathered up and brought together in one, a summit, as it were, I mean the omnipotent God of the universe. . . . It is blasphemy, then, and not a common one but the worst, to say that the Son is in any way a handiwork [creature]. . . . But if the Son came into being [was created], there was a time when these attributes did not exist; and, consequently, there was a time when God was without them, which is utterly absurd” (ibid., 1–2).

“Neither, then, may we divide into three godheads the wonderful and divine unity. . . . Rather, we must believe in God, the Father Almighty; and in Christ Jesus, his Son; and in the Holy Spirit; and that the Word is united to the God of the universe. ‘For,’ he says, ‘The Father and I are one,’ and ‘I am in the Father, and the Father in me’” (ibid., 3).

Gregory the Wonderworker

“There is one God. . . . There is a perfect Trinity, in glory and eternity and sovereignty, neither divided nor estranged. Wherefore there is nothing either created or in servitude in the Trinity; nor anything superinduced, as if at some former period it was non-existent, and at some later period it was introduced. And thus neither was the Son ever wanting to the Father, nor the Spirit to the Son; but without variation and without change, the same Trinity abides ever” (Declaration of Faith [A.D. 265]).

Sechnall of Ireland

“Hymns, with Revelation and the Psalms of God [Patrick] sings, and does expound the same for the edifying of God’s people. This law he holds in the Trinity of the sacred Name and teaches one being in three persons” (Hymn in Praise of St. Patrick 22 [A.D. 444]).

Patrick of Ireland

“I bind to myself today the strong power of an invocation of the Trinity—the faith of the Trinity in unity, the Creator of the universe” (The Breastplate of St. Patrick 1 [A.D. 447]).

“[T]here is no other God, nor has there been heretofore, nor will there be hereafter, except God the Father unbegotten, without beginning, from whom is all beginning, upholding all things, as we say, and his Son Jesus Christ, whom we likewise to confess to have always been with the Father—before the world’s beginning. . . . Jesus Christ is the Lord and God in whom we believe . . . and who has poured out on us abundantly the Holy Spirit . . . whom we confess and adore as one God in the Trinity of the sacred Name” (Confession of St. Patrick 4 [A.D. 452]).

Augustine of Hippo 

“All the Catholic interpreters of the divine books of the Old and New Testaments whom I have been able to read, who wrote before me about the Trinity, which is God, intended to teach in accord with the Scriptures that the Father and the Son and the Holy Spirit are of one and the same substance constituting a divine unity with an inseparable equality; and therefore there are not three gods but one God, although the Father begot the Son, and therefore he who is the Son is not the Father; and the Holy Spirit is neither the Father nor the Son but only the Spirit of the Father and of the Son, himself, too, coequal to the Father and to the Son and belonging to the unity of the Trinity” (The Trinity1:4:7 [A.D. 408]).

Fulgence of Ruspe

“See, in short you have it that the Father is one, the Son another, and the Holy Spirit another; in Person, each is other, but in nature they are not other. In this regard he says: ‘The Father and I, we are one’ (John 10:30). He teaches us that onerefers to their nature, and we are to their Persons. In like manner it is said: ‘There are three who bear witness in heaven, the Father, the Word, and the Spirit; and these three are one’ (1 John 5:7)” (The Trinity 4:1–2 [c. A.D. 515]).

“But in the one true God and Trinity it is naturally true not only that God is one but also that he is a Trinity, for the reason that the true God himself is a Trinity of Persons and one in nature. Through this natural unity the whole Father is in the Son and in the Holy Spirit, and the whole Holy Spirit, too, is in the Father and in the Son. None of these is outside any of the others; because no one of them precedes any other of them in eternity or exceeds any other in greatness, or is superior to any other in power” (The Rule of Faith 4 [c. A.D. 523).

The Letter of Barnabas

“And further, my brethren, if the Lord [Jesus] endured to suffer for our soul, he being the Lord of all the world, to whom God said at the foundation of the world, ‘Let us make man after our image, and after our likeness,’ understand how it was that he endured to suffer at the hand of men” (Letter of Barnabas 5 [A.D. 74], emphasis added).

Ignatius of Antioch

“Jesus Christ . . . was with the Father before the beginning of time, and in the end was revealed. . . . Jesus Christ . . . came forth from one Father and is with and has gone to one [Father]. . . . [T]here is one God, who has manifested himself by Jesus Christ his Son, who is his eternal Word, not proceeding forth from silence, and who in all things pleased him that sent him” (Letter to the Magnesians 6–8 [A.D. 110], emphasis added).

Justin Martyr

“God speaks in the creation of man with the very same design, in the following words: ‘Let us make man after our image and likeness.’ . . . I shall quote again the words narrated by Moses himself, from which we can indisputably learn that [God] conversed with someone numerically distinct from himself and also a rational being. . . . But this offspring who was truly brought forth from the Father, was with the Father before all the creatures, and the Father communed with him” (Dialogue with Trypho the Jew 62 [A.D. 155]).


“[The Father] sent the Word that he might be manifested to the world. . . . This is he who was from the beginning, who appeared as if new, and was found old. . . . This is he who, being from everlasting, is today called the Son” (Letter to Diognetus 11 [A.D. 160], emphasis added).

Irenaeus of Lyons

“It was not angels, therefore, who made us nor who formed us, neither had angels power to make an image of God, nor anyone else. . . . For God did not stand in need of these in order to accomplish what he had himself determined with himself beforehand should be done, as if he did not possess his own hands. For with him [the Father] were always present the Word and Wisdom, the Son and the Spirit, by whom and in whom, freely and spontaneously, he made all things, to whom also he speaks, saying, ‘Let us make man in our image and likeness’ [Gen. 1:26]” (Against Heresies 4:20:1 [A.D. 189], emphasis added).

Tertullian of Carthage 

“While keeping to this demurrer always, there must, nevertheless, be place for reviewing for the sake of the instruction and protection of various persons. . . . This is especially so in the case of the present heresy [Sabellianism], which considers itself to have the pure truth when it supposes that one cannot believe in the one only God in any way other than by saying that Father, Son, and Spirit are the selfsame person. As if one were not all . . . through the unity of substance” (Against Praxeas 2:3–4 [A.D. 216]).

“Keep always in mind the rule of faith which I profess and by which I bear witness that the Father and the Son and the Spirit are inseparable from each other, and then you will understand what is meant by it. Observe, now, that I say the Father is other [distinct], and the Son is other, and the Spirit is other. . . . I say this, however, out of necessity, since they contend that the Father and the Son and the Spirit are the selfsame person” (ibid. 9:1).

Athanasius of Alexandria 

“[The Trinity] is a Trinity not merely in name or in a figurative manner of speaking; rather, it is a Trinity in truth and in actual existence. Just as the Father is he that is, so also his Word is one that is and is God over all. And neither is the Holy Spirit nonexistent but actually exists and has true being” (Letters to Serapion 1:28 [A.D. 359]).

“They [the Father and the Son] are one, not as one thing now divided into two, but really constituting only one, nor as one thing twice named, so that the same becomes at one time the Father and at another his own Son. This latter is what Sabellius held, and he was judged a heretic. On the contrary, they are two, because the Father is Father and is not his own Son, and the Son is Son and not his own Father” (Discourses Against the Arians 3:4 [A.D. 360]).

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Non-Catholic Quotes:

Novatian, 3rd century antipope and founder of Novatian Heresy;

“[W]ho does not acknowledge that the person of the Son is second after the Father, when he reads that it was said by the Father, consequently to the Son, ‘Let us make man in our image and our likeness’ [Gen. 1:26]? Or when he reads [as having been said] to Christ: ‘Thou art my Son, this day have I begotten you. Ask of me, and I will give you the heathens for your inheritance, and the ends of the earth for your possession’ [Ps. 2:7–8]? Or when also that beloved writer says: ‘The Lord said unto my Lord, Sit thou on my right hand, until I shall make your enemies the stool of your feet’ [Ps. 110:1]? Or when, unfolding the prophecies of Isaiah, he finds it written thus: ‘Thus says the Lord to Christ my Lord’? Or when he reads: ‘I came not down from heaven to do mine own will, but the will of him that sent me’ [John 6:38]? Or when he finds it written: ‘Because he who sent me is greater than I’ [cf. John 14:24, 28]? Or when he finds it placed side by side with others: ‘Moreover, in your law it is written that the witness of two is true. I bear witness of myself, and the Father who sent me bears witness of me’ [cf. John 8:17–18]?” (Treatise on the Trinity 26 [A.D. 235]).

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