Historical and Orthodox
The Trinity is a foundational doctrine of the Christian faith. Throughout Church history, the doctrine of the Trinity was heavily focused on to formulate a biblical view of the Christian triune God. Councils gathered to discuss what it meant that God exists as three persons but that there is still only one God. From the church fathers’ hard work, creeds were written down to confess the catholic (lower case c meaning universal) faith about the orthodox understanding of the Trinity. The fathers concluded from God’s Word that one God exists as three distinct persons: Father, Son, and Holy Spirit.
One God
Scripture constantly testifies that there is only one true God. Deuteronomy 4:35 says, “To you it was shown, that you might know the LORD is God; there is no other besides him.” Furthermore, Isaiah 44:6 testifies, “I am the first and I am the last; besides me there is no god.” The New Testament continues this thought in James 2:19, which says, “You believe that God is one; you do well. Even the demons believe-and shudder!” Yes, even the demons are monotheists. As shown with these verses, and there are many more, God is one and there is none beside him, but Scripture also points to the plurality of God.
God as Three Distinct Persons
Beginning in the Old Testament, many names of God are used in the plural form. Actually, the first time God’s name is mentioned, in Genesis 1:1, the word Elohim is plural in Hebrew. Also, the Hebrew name Adonai is the plural form for Lord. This is more fully revealed in the New Testament. In Mark’s gospel (the earliest written gospel), we see the Father speaking from heaven, the Holy Spirit descending as a dove, and the Son being baptized (Mark 1:10-11). John testifies that the Father sent the Son and that the Father and the Son sent the Spirit (1 John 4:14, John 15:26). The Father, the Son, and the Holy Spirit are all doing distinct actions, which means they must be distinct persons. So, the Father is not the Son or the Spirit because He is not sent, the Son is not the Father or the Spirit because He is sent by the Father, and the Holy Spirit is not the Son or the Father because He was sent by the Father and the Son. The Bible also testifies that each person if fully God
Each Person as Fully God
Starting with the Father, Scripture constantly equates Him with God which is seen in (Phillipians 4:20, 1 John 3:1, 1 Corinthians 8:6 and many more). The second member of the Trinity, the Son, also called Jesus, has been said by many people that he is not fully God; however, Scripture does not back this idea. John 1:1 says, “In the beginning was the Word, and the Word was with God, and the Word was God.” John clearly states that the Word, who is Jesus, is God, not some other created being. Also, Colossians 1 talks about everything being created through Christ and Christ being preeminent. Now, just think for a moment. If everything was created through Christ, that means that Christ himself could not have been created. Therefore, Christ is eternal, making him Creator rather than a creature, and since there is only one Creator, he has to be fully God. Moreover, the church fathers used the biblical doctrine of eternal generation which will be further expounded on later. Finally, the Holy Spirit is equated with God in Acts 5:3-4 which says, “. . .Ananias, why has Satan filled your heart to lie to the Holy Spirit. . .You have not lied to man but to God.” So, what exactly is the relationship between these three distinct persons who are fully God?
Eternal Relations of Origin
The relationships between the persons of the Trinity helps us see all that has been said already. Theologians have called these the eternal relations of origin which distinguish the persons of the Trinity but maintain that there is one God. We have to ask what if God never created, or the Father never sent the Son, or the Father and the Son never sent the Spirit, what would distinguish the persons? Since the triune God we worship is eternal, the distinctions have to be founded in eternity, rather than on what the person did in creation. The roles of God the Father, God the Son, and God the Holy Spirit, in creation, help us see that there is an actual distinction between the persons. Starting with the relationship between the Father and the Son, the Father is never said to be begotten, unlike the Son. This is called paternity. In John 3:16, the apostle John says that the second member of the Trinity is the only begotten Son of God. We have already established that the Son is not created from Colossians 1, so what does it mean that the Son is begotten? This is where the doctrine of eternal generation helps. It means that the Son is eternally from the Father or is generated by the unbegotten Father. As the Nicene Creed puts it, Jesus Christ is “God of God, light of light, very God of very God.” Thus, because the Father begets His own essence, the Son is both fully God yet a distinct person. Furthermore, because the essence of God is infinite it is neither divided nor added to. Scripture applies this principle to the Holy Spirit; however, it is a different relation because the Spirit is not begotten. The term Scripture uses is procession (John 3:26) which is also called spiration by theologians. Hence, when the Word of God says that the Spirit is of God or of the Son, it means that the Holy Spirit emanates from the Father and the Son (always keep in mind that this is eternal; therefore, there is no beginning to any member of the Trinity). As demonstrated, the doctrine of eternal relations of origin is biblically founded and helps keep three distinct persons (Father, Son, Holy Spirit) of the trinity, that are each fully God, while there is still only one essence (God).
Application of Eternal Relations of Origin
In the world, we can see the triune God at work by understanding the eternal relations of origin. Starting with creation, the bible says that the Father created through the Son (1 John 1:2-3) and that the Spirit was hovering over the earth (Genesis 1:2). Applying the relations in the Trinity, the original cause is the Father because he is unbegotten, the creative cause is through the Son because he is begotten, and the perfecting cause is the Holy Spirit because he proceeds from the Father and the Son. This same principle of the Father being the author through the Son and by the Holy Spirit is seen throughout Scripture. Gregory of Nyssa says works begin from the Father, because he is unbegotten, every work is done through the Son, because He is begotten, and every work is completed by the Holy Spirit because He proceeds from the Father and the Son. We see this even in our own salvation. God the Father decides to elect people who are saved through His Son dying on the cross and are perfected by God the Holy Spirit. Also, when we pray, we pray to the Father, through the Son, and by the Holy Spirit. Hopefully, this allows us to better see the triune God at work in our lives with distinctions of the persons but unity in essence.
Conclusion
Scripture continually attests that there is only one true God that subsists as three distinct persons. This distinction lies in the eternal relations of origin. We can see how these relations affect how God interacts with the universe He created. The Trinity is a profound and complex doctrine that has biblical foundations and has developed over time. In order to worship the God we confess to believe, we must understand as Tertullian does that “We worship unity in trinity, and trinity in unity; neither confounding the persons nor dividing the substance.”
p.s. I did not use a single analogy for the trinity in this whole post because every analogy commits some sort of heresy. Just use the bible and theology to explain the trinity not analogies that commit heresy.