Catechism Lesson 1:
Who is God?

Catechism Lesson 1: Who is God?

The Catholic Church teaches that God revealed Himself to mankind as a Trinity of Persons – the Father, the Son and the Holy Spirit. This doctrine is called the Holy Trinity.

The Holy Trinity is the mystery of one God in three Persons: Father, Son and Holy Spirit. The Holy Trinity is the central mystery of Christian faith and life; it is the mystery of God in Himself; it is the source of all the other mysteries of faith, and it is the most fundamental and essential teaching in the hierarchy of the truths of faith. The history of salvation is aligned to the way in which the Father, Son and Holy Spirit was revealed to men. (CCC 234)

How were the Persons of the Holy Trinity revealed to us?

  1. The Son was revealed by the Father:
    • At the baptism of Jesus, a voice from heaven said, “This is my beloved Son, with whom I am well pleased. (Matthew 3:17; Mark 1:11; Luke 3:22)”
    • At the Transfiguration, a voice from a cloud said, ““This is my beloved Son, with whom I am well pleased; listen to him. (Matthew 17:5; Mark 9:7; Luke 9:35)”
  2. The Father was revealed by the Son. Jesus revealed His heavenly Father: “No one knows the Son except the Father, and no one knows the Father except the Son, and anyone to whom the Son chooses to reveal Him.” (CCC 240; Matthew 11:27)
  3. The Holy Spirit was revealed by the Son. Jesus announced the sending of the Holy Spirit to His disciples: “I will ask the Father, and he will give you another Advocate to be with you always, the Spirit of truth (John 14:16-17); the Advocate, the Holy Spirit that the Father will send in my name—He will teach you everything and remind you of all that I told you (John 14:26).”

During the first centuries, the Church sought to clarify its Trinitarian faith in the early Church councils, and aided by the theological work of the Church Fathers (CCC 250). The Church developed the term “substance” to designate the divine being in its unity, the term “person” to designate the Father, Son and Holy Spirit, and the term “relation” to designate their distinction from one another. (CCC 251-252)

The Holy Trinity is One. The Church confesses one God in three Persons, and not three gods. But at the same time, the three Persons do not share one divinity among themselves, but each Person is God whole and entire. (CCC 253)

  1. Each Person is distinct from one another. The Father is not the Son or the Holy Spirit, the Son is not the Father or the Holy Spirit, the Holy Spirit is not the Father or the Son. (CCC 254)
  2. Each Person is relative to one another. The Father is related to the Son, the Son is related to the Father, and the Holy Spirit is related both to the Father and the Son. However, while all three Persons are distinct from one another, all three Persons are of one and the same substance. (CCC 255)

The whole Christian life is a communion with each of the divine Persons without separating them. Everyone who glorifies the Father does so through the Son in the Holy Spirit; everyone who follows Christ does so because the Father draws him and the Spirit moves him. (CCC 259; John 6:44, Romans 8:14) The Lord Jesus Christ said, “If a man loves me, he will keep my word, and my Father will love him, and we will come to him, and make our home with him.” (John 14:23)

This is the Catholic faith: we worship one God in the Trinity and the Trinity in unity, without either confusing the Persons or dividing the substance; for the Person of the Father is one, the Person of the Son is another, and the Person of the Holy Spirit is yet another; but the Godhead of the Father, Son and Holy Spirit is one, their glory equal, their majesty coeternal. (CCC 266; Athanasian Creed)

Prayer: Nicene Creed

I believe in one God, the Father almighty, Maker of heaven and earth, of all things visible and invisible.

I believe in one Lord Jesus Christ, the Only Begotten Son of God, born of the Father before all ages. God from God, Light from Light, true God from true God, begotten, not made, consubstantial with the Father; through Him all things were made. For us men and for our salvation, He came down from heaven, and by the Holy Spirit was incarnate of the Virgin Mary, and became man. For our sake He was crucified under Pontius Pilate, He suffered death and was buried, and rose again on the third day in accordance with the Scriptures. He ascended into heaven and is seated at the right hand of the Father. He will come again in glory to judge the living and the dead and His kingdom will have no end.

I believe in the Holy Spirit, the Lord, the Giver of life, who proceeds from the Father and the Son, who with the Father and the Son is adored and glorified, who has spoken through the prophets. I believe in one, holy, catholic and apostolic Church. I confess one Baptism for the forgiveness of sins and I look forward to the resurrection of the dead and the life of the world to come. Amen.


  1. What is the name that God revealed Himself to Moses? (Hint: Exodus chapter 3)
  2. How is the Holy Trinity revealed in the Bible? (Hint: Matthew 28:19, John 14:15-17, John 14:26)
  3. How is the Father revealed in the Bible? (Hint: John 3:16, John 5:17, John 14:10, Luke 23:46)
  4. How is Jesus Christ revealed as God in the Bible? (Hint: John 1:1, John 10:30)
  5. How is the Holy Spirit revealed in the Bible? (Hint: Genesis 1:1-2, Isaiah 11:1-2, Acts 2:1-4, Ephesians 1:13-14)