“There is only one unbegotten Being, God, even the Father; and an only begotten Son, God, the Word, and man; and one Comforter, the Spirit of truth. – Ignatius of Antioch.
Any discussion of God is a discussion of a great mystery. And at the heart of this mystery is the rather extraordinary assertion of Christians that God is a trinity.
In this book, I will endeavor to provide an introduction to this mystery. I will talk about each of the three persons of the Trinity and try to explain their relationship.
Before beginning this work, it is useful to explain what Catholicism understands by the Trinity. God is an essence (or nature) composed of three persons. The essence or nature is what a thing is. For example, human beings have a human (and therefore rational) nature. The essence of God is Divine. A person is what a thing is. A person can be a man or a woman, a parent or a sibling. In God, the three persons are the Father, the Son and the Holy Spirit.
To define something is to limit it. Only then can distinctions be made. This fact leads to an immediate problem in theology. The God of the Bible is infinite. What is infinite is not limited to time or space. This fact makes an essential definition of God impossible. Therefore, any discussion of God often involves the use of analogies. One such analogy is God as Father.
The concept of God as father is drawn from several sources; I will cite just two. The first is that God is the very source of existence; God engenders creation as a human father engenders a child. However, we miss the language. God does not bring the universe into creation as a human father brings a child into the world. On the contrary, the Word of God is creative, He speaks, and it is done. Evidence of God’s creative Word appears in Genesis: “And God said, ‘Let there be light, and there was light.’ (Genesis 1:3). This creative Word of God has important implications for the Son, as we will see below. (Catechism of the Catholic Church, paragraph 291).
For Saint Augustine (and later, for Thomas Aquinas), God the Father is the principle without principle. This means that God the Father is not caused or generated by another. This concept of the Father as principle without principle is essential to understanding the relationship between the Father, the Son, and the Holy Spirit. The Trinity is the inner life of God. The Father knows himself by reason, and that is Christ. And knowing himself, he loves himself, and that’s the Holy Spirit.
The Son of God is, of course, Jesus Christ. The Son is begotten by the Father, who constitutes the Person of the Son. As such, Catholicism asserts that Christ is the second person of the Holy Trinity.
This does not mean that this generation is ontological or temporal. Instead, the Father actively and eternally begets the Son. This is the meaning intended in the prologue of the Gospel of John. “In the beginning was the Word, and the Word was with God, and the Word was God.”
Notice, before creation the Son was with the Father. This is to emphasize that there is no essential distinction between the Person of the Father and that of the Son. Moreover, this relationship between two people has no beginning in time because it existed before creation, from all eternity. Thus, while the Father and the Son are distinct as persons, they are one with respect to their divine essence.
The Father and the Son actively draw the Holy Spirit into the one relationship within the inner life of God. Spire, not begotten, because the Father and the Son are already personified with respect to each other in the first two relationships. For this reason, the Catechism teaches that “The second person of the Holy Trinity is Son only in relation to his Father”.
The Holy Spirit
The Holy Spirit is the love between the Father (who is the lover) who knows and loves himself (who is the Son as well as the beloved). Therefore, the Holy Spirit is inspired by the Father and the Son, constituting the Person of the Holy Spirit.
In other words, the Holy Spirit proceeds from the Father and the Son, but not in a generative sense, but a spiration. “Spiration” comes from the Latin word for “spirit” or “breath”.
In John 20:22, it is said that Jesus “breathed on them and said to them, ‘Receive the Holy Spirit.’ The Scriptures reveal that the Holy Spirit belongs to “the love of God [that] has been poured into our hearts” (Romans 5:5).
As said above, the Holy Spirit is the reciprocal love of the Father for the Son and of the Son for the Father (John 15:26). Thus, the procession of the Holy Spirit is not intellectual and generative but has its origin in the will of God and the ultimate act of the will, which is love.
By understanding God (which cannot be completely done), we recognize that the Father is the first principle of life, and that the Son is the knowing a which proceeds from the Father. Finally, the Holy Spirit – he who wills – is the bond of love between the Father and the Son and therefore proceeds as the love of the Father and the Son.
It may be helpful to understand the three persons of the Trinity by virtue of their work. For example, the Father in creation, the Son in Salvation and the Holy Spirit at Pentecost. Again, however, we cannot separate the work of one person of the Trinity from another as they are one in essence. “Because it does not divide the divine unity, the real distinction of the Persons from each other lies only in the relations which connect them to each other” (Catechism of the Catholic Church, paragraph 255). In other words, the Father reveals the Son, the Son reveals the Father, and the Holy Spirit reveals the Father and the Son.
For this reason, the Catechism states: “The Divine Persons are also inseparable in what they do. But in the unique divine operation, each manifests what is proper to him in the Trinity, notably in the divine missions of the Incarnation of the Son and the gift of the Holy Spirit.