Chapter 5 | The Trinity

Matthew 28:19-20, “19 Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, 20 and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age."

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

God the Father, Son, and the Holy Ghost 
The New Testament, along with the Old, clearly teaches the triune nature of God.  Though it was not until the Council of Nicea that all the terms were defined and clearly written out for everyone to understand, it can be most easily seen in the writings of the earliest church Fathers.  It was a core belief to the early church that Jesus and Holy Spirit was as much God as the Father was.  Therefore, in their writings the Father, Son, and Holy Spirit are always seen as the one divine being which is called God, and yet three distinct persons with different roles and activity.
Here are the writings of the fathers and their view of the nature of God, also known as the trinity. 

Justin Martyr, First Apology, Chapter 6 | 160AD

In Justin’s letter of defense to the Romans he clearly states that Christians are not “atheists” on account they do not worship the Roman pagan gods, but rather worship the one true God revealed in Scripture.  And in this chapter Justin clearly defines that he and the Christians of his day worshipped and adored the Father, Son, and the Holy Spirit as the “most true God.”

“Hence are we called atheists. And we confess that we are atheists, so far as gods of this sort are concerned, but not with respect to the most true God, the Father of righteousness and temperance and the other virtues, who is free from all impurity. But both Him, and the Son (who came forth from Him and taught us these things, and the host of the other good angels who follow and are made like to Him), and the prophetic Spirit, we worship and adore, knowing them in reason and truth, and declaring without grudging to every one who wishes to learn, as we have been taught”.

Irenaeus, Against Heresies, Book 4, Chapter 20, Verse 5 | 180AD

In this letter Irenaeus clearly shows the difference in the persons and roles of the one true God.  This proves that the early church had no problems believing that the Father, Son, and Holy Spirit were one and the same God, but at the same time were different persons with different roles.  Irenaeus states that the one God has been seen through the Spirit, the Son, and the Father and that each divine person complements the other and works together to bring eternal life to man.

“For God is powerful in all things, having been seen at that time indeed, prophetically through the Spirit, and seen, too, adoptively through the Son; and He shall also be seen paternally in the kingdom of heaven, the Spirit truly preparing man in the Son of God, and the Son leading him to the Father, while the Father, too, confers [upon him] incorruption for eternal life, which comes to every one from the fact of his seeing God.”

Tertullian, Letter on Modesty, Chapter 21 | 198AD

Tertullian was known to be the first to adopt the term “trinity” to define the unity of the three divine persons.  This is not to say he was the first to believe that the Father, Son, and the Holy Spirit were the true God, but he was the first to begin to try to explain the nature of God with terms that people would remember.  Therefore, he is the first father to use the term “trinity” to describe God’s nature. 
It is good for the reader to note that he is not in a place in this letter of stating new doctrine but rather he is making a point about the state of the church and he then refers to the nature of God as an example for the unity of the church.  This proves that equality and unity of God within the three divine persons was not “new doctrine,” but rather accepted as common and was understood to be true by ever Christians of his day.

“For the very Church itself is, properly and principally, the Spirit Himself, in whom is the Trinity of the One Divinity—Father, Son, and Holy Spirit.”

Tertullian, Letter Against Praxeas, Chapter 9 | 213AD

At the end of Tertullian’s life he could clearly define and defend the orthodox Trinitarian view of God’s nature.  Here in this letter against the heresies of Praxeas Tertullian writes chapter after chapter on the triune nature of God.  He uses many scriptures and examples from the Bible to prove that God is the Father, Son, and the Holy Spirit.  His teachings would prove very instrumental in the coming years against such attacks like those of Arius who would deny Jesus’ and the Holy Spirit’s divinity.
Also, Tertullian was useful in defeating the heresy that God was one person who took different forms called the Father, Son, and the Holy Spirit.  He states in this passage that the Father, Son, and the Spirit are “inseparable,” but yet they are distinct from each other as persons.  This is important to know because some people of his day tried to say that the Father was the Son in the form of man and the Son was the Spirit in spiritual nature, thus making them all one person, but appearing in different forms.[1]  Tertullian clearly states that the Father, Son, and Holy Spirit is the same one God, but yet three distinct persons, meaning, the Father is not the Son, and the Son is not the Holy Spirit, yet they are the one in the same God.

“Bear always in mind that this is the rule of faith which I profess; by it I testify that the Father, and the Son, and the Spirit are inseparable from each other, and so will you know in what sense this is said. Now, observe, my assertion is that the Father is one, and the Son one, and the Spirit one, and that They are distinct from Each Other.”

Cyprian, Treatises, Chapter 1, Verse 6 | 250AD

Cyprian was a great defender and teacher of the trinity.  As with the other church fathers Cyprian understood the belief for the trinity as being orthodox and accepted by all Christians.  Many times in his writings he uses the trinity to defend other points, such as the unity of the church.  Therefore, his writings serve along side of Tertullian as another example of the wide and uniformed acceptance of the trinity.
Here in this verse he states that Jesus was one with the Father in the same sense the Spirit is one with the Father and Son.  And thus all three persons- the Father, Son, and Spirit are all one God.

“The Lord says, “I and the Father are one;” and again it is written of the Father, and of the Son, and of the Holy Spirit, “And these three are one.”   And does any one believe that this unity which thus comes from the divine strength and coheres in celestial sacraments, can be divided in the Church, and can be separated by the parting asunder of opposing wills? He who does not hold this unity does not hold God’s law, does not hold the faith of the Father and the Son, does not hold life and salvation.”


1. Describe the Trinity.

2. Defend the trinity from the church father’s use of the New Testament.

3. Explain how the trinity predates the Council of Nicaea.

4. Pray that you can teach the triune nature of God with clarity and authority.


1. "The Forgotten Trinity," by James White.

[1] This teaching is known today as “oneness” but was called modalism, modalistic monarchianism, and Sabellianism in the third century and was made popular by Sebellius.