The Doctrine of the Trinity in the Orthodox Church
The Orthodox West and East understood the monarchy of the Father and the unique causal principle of the Spirit. Both Sts. Augustine and Gregory Palamas teach the Orthodox understanding of the persons of the Trinity.
The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all.
2 Corinthians 13:14
The most important doctrinal pillar of the Orthodox Church is that of the Most Holy Trinity. It was revealed to us by Jesus Christ through His apostles, and they through the Holy Fathers who were commissioned to precisely define the doctrine in the Holy Ecumenical Councils. This dogma teaches us that God is one in essence, but three in hypostases (or persons). Because of this, it is one of the most controversial doctrines since it distinguishes the Orthodox Church from the other churches of the West.
The Orthodox Church firmly confesses that there is only God in three distinct persons: the Father, the Son, and the Holy Ghost. For us, God exists in three divine persons who intimately maintain unity and communicate with each other naturally, totally, eternally, and inseparably. However, every one of these persons maintains His own identity and unique characteristics without confusion or mixture with the others.
The unity of the operations in the Most Holy Trinity does not occur as a created series whose unity is analogical. Rather, it is a singular unity in its most literal sense. Here, for the Orthodox Faith, if the divine essence is one, its operation (or energy) is also one. The three persons distinguish themselves—one from another—by their proper personal characteristics, even while sharing the same divine essence. The Father, in His mode of existence, is uncaused (agennetos). The Son, in His mode of existence, is begotten (gennetos). The Holy Spirit, in His mode of existence, proceeds (ekporeuetai). These three modes, or individual characteristics, express the eternal relation of the divine persons in God.
In short, we have that the Father is one, the Son another, and the Holy Spirit another; in hypostasis, each is distinct, but in nature they are the same. In this sense, Jesus says: ‘The Father and I are one’. He teaches us that ‘one’ refers to his nature and ‘we are’ to his hypostases.
St. Fulgentius of Ruspe, The Trinity
We must know and understand that the Orthodox Faith confesses that there is only one God who exists before all, above all, and in all: the Father. We find this confession in the Nicene-Constantinopolitan Creed; we confess ‘one God’ who is ‘the Father Almighty’. The Father is completely uncaused and only He is the foundation and fount of divinity, contemplated in the Son and the Holy Spirit. Only He is the author, initial uncaused cause of all which exists, whether visible or invisible. As St. Thalassios teaches:
We regard the Father as unoriginate and as the source: as unoriginate because He is unbegotten, and as the source because He is the begetter of the Son and the sender forth of the Holy Spirit, both of whom are by essence from Him and in Him from all eternity.
4th cent., par. 92
That is to say, there only exists one sole cause and one sole principle (arce) in God: the hypostasis of the Father. St. Gregory Palamas refers to the Father as the ‘generating principle in God’ (theotes theogonos ho Pater) of the Son and the Holy Spirit, who take their subsistence from Him. In this communion (κοινωνίᾱ) with their head, both persons are equal with Him in their essence, glory, and energy.
As we can observe, in the Trinitarian economy explicated by the Orthodox Church, the focus of attention is situated always on the monarchy of the Father, who, as the unique fount of divinity, causes the hypostasis of the Son by generation and the hypostasis of the Holy Spirit by procession. By this, we safeguard the dogma of the Unity in the Trinity, situating it in the sole fount of divinity.
The Father has one sole Son, who, on the hand, does not have principle because He is eternal, but, on the other hand, does not lack principle because He has the Father as principle, foundation, and font; only from the Father springs forth from before all ages incorruptible form, without change, impassible, by generation, without suffering any division, being God of God. He is called called the ‘Word’ or ‘Logos’ of God, just as the evangelist teaches in John 1:1.
This can be illustrated by the Father being the ‘Supreme Mind’ who possesses in Himself the ‘Supreme Word’ who is ‘always coexistent with the Mind’. It is in the Word where the Father possesses perfect knowledge of ‘all that which is good’. If the Father is eternal, without principle and uncreated, then the Word shares the same attributes of the Father. There never has been, neither is, neither will be a single moment in which the Son is not with and in the Father. The Father and the Son are eternally united, as the Scriptures teach.
The Word (or Logos) is called ‘Son’, because He is begotten by the Father from eternity and is completely identical to the Father in essence. His cause and principle is the Father. The Son is not the author and principle of the Trinity's intelligible Divinity but is He by which all created things that were made are made.
St. Ambrose, in his homily on the Gospel of St. Luke, mentions:
The Son is first, and by consequence, co-eternal, because He has the Father, with whom He is eternal.
The Son is the perfect image of the Father, as St. Paul teaches in his epistle to the Colossians.
The Holy Ghost
The Holy Ghost, in Orthodox theology, can be considered as the eternal love from the Father to the Son. To better explain this, we must ground ourselves in St. Augustine’s On the Trinity and St. Gregory Palamas’ 150 Sentences. When the Father begets the Son, He loves Him and the love leaves (or proceeds) from the Father and arrives at the Son. Thus, in the Trinity three figures are present: the Beloved, the Lover, and the Love in this Communion. The Love by which the Father loves the Son is the Holy Ghost, and His existence manifests the consubstantiality of the Father and the Son.
Understanding this, the Orthodox Church confesses that the Holy Ghost has the Father (the Lover) as His causal principle, but He is manifested eternally by means of being received by the Son (the Beloved). Thus, when the Orthodox West encountered Arians doubting this doctrine, it explained the consubstantiality of the Father and the Son with the Holy Ghost.
Patriarch Gregory of Cyprus, to explain this, used an analogy to explain illustrate the Orthodox position. We can take the sun as representing the Father, the rays as the Son, and the light (or splendour) as the Holy Ghost. Now, as Patriarch Gregory teaches, the rays transmit the light of the sun, but they are not the source of the light, that is to say, they do not cause the existence of the of the light, neither do they add anything, because only the sun itself causes the light. Part of this analogy is that the teachings of the Holy Fathers of the Church can be understood, who said that the Holy Ghost proceeds from the Father by means of the Son. This is how the Orthodox understand that phrase.
In contrast, in the Modern West, there exists a confusion between the hypostatic origin of the Holy Ghost (uniquely from the Father) and His eternal manifestation (from the Father by means of the Son). By not differentiating between both, and by believing that the consubstantiality of the Father and the Son requires the Spirit to proceed hypostatically from both, the Modern West ends up either confusing the persons of the Father and the Son or affirming that the Father's characteristic of being unoriginate and the principle of the other persons of the Trinity is not proper to His person but to the divine essence. And if what distinguishes the Son and the Spirit is hypostatically identical to the Father, then Sabellianism is unavoidable.
Worst of all, the modern western confusion loses the reality of the communal love of the Trinity and the Holy Ghost as Love and Gift. For if the Son causes the person of the Holy Ghost, how could He receive Him as Love and Gift?
As we can see, the Orthodox Faith confesses faithfully the doctrine of the Most Holy trinity and safeguards the teaching of the Monarchy of the Father, that He is the unique causal principle of the Divine Persons. This distinguishes the faith from later western conceptions which use other methods of explanation (such as Thomas of Aquinas' relations of opposition, the even later Protestant theologies, and others which we will see later).
This belief is the foundation of the Nicene-Constantinopolitan Creed, which all Orthodox recite in the Mass, recounting the mystery of God revealed to us by means of Christ Jesus.