The unity and Trinity of God

Question 21

Is there but one God?

Yes; there is but one God.

Question 22

Why can there be but one God?

There can be but one God, because God, being supreme and infinite, cannot have an equal.

Question 23

How many Persons are there in God?

In God there are three Divine Persons, really distinct, and equal in all things—the Father, the Son, and the Holy Ghost.

Question 24

Is the Father God?

The Father is God and the first Person of the Blessed Trinity.

Question 25

Is the Son God?

The Son is God and the second Person of the Blessed Trinity.

Question 26

Is the Holy Ghost God?

The Holy Ghost is God and the third Person of the Blessed Trinity.

Question 27

What do you mean by the Blessed Trinity?

By the Blessed Trinity I mean one God in three Divine Persons.

Question 28

Are the three Divine Persons equal in all things?

The three Divine Persons are equal in all things.

Question 29

Are the three Divine Persons one and the same God?

The three Divine Persons are one and the same God, having one and the same Divine nature and substance.

Question 30

Can we fully understand how the three Divine Persons are one and the same God?

We cannot fully understand how the three Divine Persons are one and the same God, because this is a mystery.

Question 31

What is a mystery?

A mystery is a truth which we cannot fully understand.

One God

Questions 21, 22

The opening questions affirm God's uniqueness. They provide the setting for everything that follows: the lesson does not introduce three gods. Read Deuteronomy's confession of the one Lord alongside Matthew's baptismal command.

Father, Son, and Holy Spirit

Questions 23, 24, 25, 26, 27

Holy Ghost is the older English expression for Holy Spirit. The names identify distinct persons, not changing roles or three parts of God. The Catechism's terminology distinguishes the unity of divine nature from the distinction of persons.

Equality without division

Questions 28, 29

First, second, and third do not rank the persons by age or power. Each is fully God. John 1 speaks of the Word both with God and as God; Matthew names Father, Son, and Spirit together in baptism.

Understanding a mystery

Questions 30, 31

Mystery does not mean that words have no meaning. It means that revealed truth exceeds complete human comprehension. Study should clarify what is affirmed while recognizing those limits. Avoid illustrations that quietly turn the persons into parts or successive appearances.

Deuteronomy 6:4–9

Israel's confession of the one Lord is expressed through love, teaching, and daily life.

4 Hear, O Israel: The Lord our God is one Lord: 5 And thou shalt love the Lord thy God with all thine heart, and with all thy soul, and with all thy might. 6 And these words, which I command thee this day, shall be in thine heart: 7 And thou shalt teach them diligently unto thy children, and shalt talk of them when thou sittest in thine house, and when thou walkest by the way, and when thou liest down, and when thou risest up. 8 And thou shalt bind them for a sign upon thine hand, and they shall be as frontlets between thine eyes. 9 And thou shalt write them upon the posts of thy house, and on thy gates.

Matthew 28:16–20

Jesus' commission explicitly joins Father, Son, and Holy Spirit in the baptismal name.

16 Then the eleven disciples went away into Galilee, into a mountain where Jesus had appointed them. 17 And when they saw him, they worshipped him: but some doubted. 18 And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. 19 Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: 20 Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen.

John 1:1–5

The Gospel's opening identifies the Word in relation to God and to creation.

1 In the beginning was the Word, and the Word was with God, and the Word was God. 2 The same was in the beginning with God. 3 All things were made by him; and without him was not any thing made that was made. 4 In him was life; and the life was the light of men. 5 And the light shineth in darkness; and the darkness comprehended it not.