The Unity and Trinity of God

The Hospitality of Abraham - 6th century.

I believe in God the Father Almighty… in Jesus Christ, His only Son our Lord… and in the Holy Ghost...

What does the Trinity of God mean?
Trinity of God means that in God there are three equal Persons, really distinct: Father, Son, and Holy Ghost.

What does three persons really distinct mean? 
Three persons really distinct means that in God one Person is not the other, yet all three are only one God.

Do we understand how the three divine Persons, although really distinct, are only one God?
We do not understand nor can we understand how the three divine Persons, although really distinct, are only one God: it is a mystery.

Who is the first Person of the Most Holy Trinity?
The first Person of the Most Holy Trinity is the Father.

Who is the second Person of the Most Holy Trinity?
The second Person of the Most Holy Trinity is the Son.

Who is the third Person of the Most Holy Trinity?
The third Person of the Most Holy Trinity is the Holy Ghost.

Why is the Father the first Person of the Most Holy Trinity?
The Father is the first Person of the Most Holy Trinity because He does not proceed from another Person, and because from Him proceed the other two, that is, the Son and the Holy Ghost.

Why is the Son the second Person of the Most Holy Trinity?
The Son is the second Person of the Most Holy Trinity because He is begotten of the Father, and because, together with the Father, He is the principle of the Holy Ghost.

Why is the Holy Ghost the third Person of the Most Holy Trinity?
The Holy Ghost is the third Person of the Most Holy Trinity because He proceeds from the Father and from the Son.

Is each Person of the Most Holy Trinity God?
Yes, each Person of the Most Holy Trinity is God.

If each divine Person is God, then are the three divine Persons three Gods?
The three divine Persons are not three Gods, but only one God, because They have the one and same unique nature or divine substance.

Are the three divine Persons equal, or is one greater, wiser or more powerful?
Since the three divine Persons are one God, they are equal in every respect, and have equally in common every perfection and every operation. However, certain perfections and their corresponding works are attributed rather to one Person than to another, such as power and creation are attributed to the Father.

Did at least the Father exist before the Son and the Holy Ghost?
The Father did not exist before the Son and the Holy Ghost because the three divine Persons, having in common the unique divine nature which is eternal, are equally eternal

From the Catechism of the Christian Doctrine, by S. S. Pius X, 1912.


The Trinity, parchment by Taddeo Crivelli, from a manuscript from 1460–70; in the J. Paul Getty Museum, Los Angeles.

The Unity Of Nature In God

It must also be confessed that there is but one God, not many gods. For we attribute to God supreme goodness and infinite perfection, and it is impossible that what is supreme and most perfect could be common to many.

If a being lack anything that constitutes supreme perfection, it is therefore imperfect and cannot have the nature of God.

The unity of God is also proved from many passages of Sacred Scripture. It is written: Hear, O Israel, the Lord our God is one Lord; again the Lord commands: Thou shalt not have strange gods before me; and further He often admonishes us by the Prophet: I am the first, and I am the last, and besides me there is no God. The Apostle also openly declares: One Lord, one faith, one baptism.

It should not, however, excite our surprise if the Sacred Scriptures sometimes give the name of God to creatures. For when they call the Prophets and judges gods, they do not speak according to the manner of the Gentiles, who, in their folly and impiety, formed to themselves many gods; but express, by a manner of speaking then in use, some eminent quality or function conferred on such persons by the gift of God.

The Trinity Of Persons In God

The Christian faith, therefore, believes and professes, as is declared in the Nicene Creed in confirmation of this truth, that God in His Nature, Substance and Essence is one. But soaring still higher, it so understands Him to be one that it adores unity in trinity and trinity in unity.


The Doctrine Of The Trinity

In the one Substance of the Divinity the Father is the First Person, who with His Only-begotten Son, and the Holy Ghost, is one God and one Lord, not in the singularity of one Person, but in the trinity of one Substance. These Three Persons, since it would be impiety to assert that they are unlike or unequal in any thing, are understood to be distinct only in their respective properties.

For the Father is unbegotten, the Son begotten of the Father, and the Holy Ghost proceeds from both.

Thus we acknowledge the Essence and the Substance of the Three Persons to be the same in such wise that we believe that in confessing the true and eternal God we are piously and religiously to adore distinction in the Persons, unity in the Essence, and equality in the Trinity.

Hence, when we say that the Father is the First Person, we are not to be understood to mean that in the Trinity there is anything first or last, greater or less. Let none of the faithful be guilty of such impiety, for the Christian religion proclaims the same eternity, the same majesty of glory in the Three Persons. But since the Father is the Beginning without a beginning, we truly and unhesitatingly affirm that He is the First Person, and as He is distinct from the Others by His peculiar relation of paternity, so of Him alone is it true that He begot the Son from eternity. For when in the Creed we pronounce together the words God and Father, it means that He was always both God and Father.

Practical Admonitions Concerning

The Mystery Of The Trinity Since nowhere is a too curious inquiry more dangerous, or error more fatal, than in the knowledge and exposition of this, the most profound and difficult of mysteries, let the pastor teach that the terms nature and person used to express this mystery should be most scrupulously retained; and let the faithful know that unity belongs to essence, and distinction to persons.

But these are truths which should not be made the subject of too subtle investigation, when we recollect that he who is a searcher of majesty shall be overwhelmed by glory. We should be satisfied with the assurance and certitude which faith gives us that we have been taught these truths by God Himself, to doubt whose word is the extreme of folly and misery. He has said: Teach ye all nations, baptising them in the name of the Father, and of the Son, and of the Holy Ghost; and again, there are three who give testimony in heaven, the Father, the Word, and the Holy Ghost; and these three are one.

Let him, however, who by the divine bounty believes these truths, constantly beseech and implore God and the Father, who made all things out of nothing, and ordereth an things sweetly, who gave us power to become the sons of God, and who made known to the human mind the mystery of the Trinity, let him, I say, pray unceasingly that, admitted one day into the eternal tabernacles, he may be worthy to see how great is the fecundity of the Father, who contemplating and understanding Himself, begot the Son like and equal to Himself, how a love of charity in both, entirely the same and equal, which is the Holy Ghost, proceeding from the Father and the Son, connects the begetter and the begotten by an eternal and indissoluble bond; and that thus the Essence of the Trinity is one and the distinction of the Three Persons perfect.

Extracts from the Catechism of the Council of Trent