From the Mystery of the Most Holy Trinity
There is only one God.
There are three persons in God.
These three persons are the Father, the Son, and the Holy Spirit, and this is what we call the Holy Trinity.
The Father is God.
The Son is God.
The Holy Spirit is God.
They are three distinct persons, yet they are one God.
They are only one God, because they have only one and the same nature, one and the same divinity.
These three divine persons all have the same greatness, the same wisdom and the same power.
The Father is not older than the Son and the Holy Spirit. They are all three from the same eternity. Finally, they are equal in all things, because they are one God.
EXPLANATION
It is God who is the creator of this universe, and it is he who preserves it. He created us free, and he wants us to use our freedom to honor him by believing what he tells us, although we do not understand it, and by doing what he commands us, whatever he commands. could cost us.
God has revealed mysteries to us, that is to say, obscure truths that our limited reason cannot reach. However incomprehensible they may be, we must know what they consist of, and we must believe them on the infallible word of a God, the truth itself, which cannot deceive us. We cannot be saved if we refuse to believe them.
However impenetrable the mysteries that concern God may be, it is very reasonable to believe them, since it is on the word of God, the sovereign truth, that they are believed. And it is not surprising that we cannot understand the mysteries; God being by his nature the infinite Being, he is necessarily incomprehensible.
The first of the mysteries, which was almost unknown before the coming of Jesus Christ, is the mystery of the Most Holy Trinity.
By the Most Holy Trinity we understand a single God in three truly distinct persons, each of whom has the same divinity.
The first of these persons is the Father, the second is the Son, the third is the Holy Spirit.
The Father is God, the Son is God, the Holy Spirit is God. These people are not the same; they are truly distinguished, and nevertheless they are only one and the same God, because they have only one and the same nature; so no one is greater, wiser or more powerful than the other. The three divine persons have the same greatness, the same wisdom and the same power. The Father is not older than the Son; the Father and the Son are not older than the Holy Spirit: all three are eternal and equal in all things; they are only one God.
We do not understand how there is only one God in three distinguished persons, each of whom is God; but it is a mystery, that is to say an incomprehensible truth: must there not be truths that the human mind, which is finite, cannot conceive in the religion of a God who is a to be infinite? This mystery, as well as the other mysteries, are not against reason, since reason sees no contradiction in it; but they are above reason, that is to say, beyond its reach.
The mysteries that God has revealed to us, far from being useless, serve greatly to make us aware of the holiness, justice and mercy of God.
A proof that it is God who revealed the mystery of the Holy Trinity and the other mysteries is that it is only God who could have given us the idea; it is that only God could have made them believe; it is because only God has been able to preserve faith in the universe.
Not only does reason not oppose the belief in the mystery of the Holy Trinity and the other mysteries of Christianity, but it also says that we must believe them despite their obscurity, because the proofs of the divinity of the Christian religion are invincible, and that the obscurity of the mysteries is essential to a divine faith.
There must be, in a revealed divine religion, mysteries, obscure truths, either because of the object of faith, which is the nature of God, or because of the end of faith, which is to submit the spirit of man to God, and to provide him, through this submission, with the opportunity to merit, or finally because of the use of faith, since the way which leads to faith, the principle of justification and salvation, must be the same for all, for those whose minds are the most limited, as for those whose minds are the most enlightened; but would that be, if there were not for all men, even for those who have more intelligence and knowledge, obscure truths, mysteries.
Here is what Bossuet said to instruct the faithful on the ineffable mystery of the Holy Trinity, not claiming to give them knowledgeclear, but an idea of a mystery which, by the very fact that it is a mystery, is incomprehensible.
God, who is necessarily eternal, was not idle before creation: he acted continually, since a spirit cannot cease to act. Always occupied with himself, he contemplated himself. This contemplation produced perfect knowledge; from this eternal and perpetual contemplation which produced infinite knowledge, came infinite love.
We call God the Father, the first person who knows; we call God the Son, the perfect knowledge, the substantial image that the one who contemplates himself produces in himself, and this is the second person; we call the Holy Spirit the infinite and consubstantial love which proceeds from contemplation and knowledge; it's the third person.
That which knows is well distinguished from that which is known, and likewise the effect which results from it is not the same; these persons are therefore not the same, and they are equal, since everything that is in God is eternal, perfect, divine; each of them is therefore God. However, we cannot say that these are three Gods. They are only one, since it is God who contemplates himself and who loves himself.
There are in our soul, which is a pure created spirit, three things which we distinguish well, the faculty of thinking or memory , the faculty of judging or understanding , and the faculty of desire, of rejoicing, of love, or will . There is no doubt that it is the same soul which thinks, which judges and which wills. We clearly see, by this comparison, however defective it may be, that it is not repugnant to there being one God in three distinguished persons who are God. Could we not say: In God, the power that thinks is the Father ; the wisdom of the Father who judges is the Son ; the power that rejoices, that loves, is the Holy Spirit ?
Let us not just believe in the Most Holy Trinity; let us further animate our faith on what it teaches us concerning this ineffable mystery, and let us pay to the three divine persons the tribute of religion due to them, by adoring them with the deepest respect.
HISTORICAL FEATURES
A man of genius, who was walking on the seashore, was occupied with the mystery of the Holy Trinity. He sought to delve into it, forgetting what is written, that he who attempts to fathom the depths of the majesty of God will be oppressed by his glory. He then saw near him a little child who never stopped going to take water from the sea in a shell, and returning to put this water in a hollow which was in the earth. He spoke to him: What do you intend to do, my child, by putting the water you are going to fetch into this hollow? Put all the sea water in it, he replied. He couldn't help but laugh at its simplicity. This child noticed this and said to him: So you think that I will not succeed? I assure you that I will put all the water of the sea into this hole, rather than you put into your head the mystery of the Holy Trinity until you understand it: the mind of man is too limited; how could what is finite contain God who is an infinite being? This reckless man recognized that it was God who gave him a salutary lesson through the mouth of this child; and he no longer sought to plumb the depths of a mystery which is impenetrable to every mortal. This man of genius is Saint Augustine.
Two people blind from birth were talking together: one of them was ignorant and impious, but the other was learned and pious. The Godless Blind Man: I would like to know what God was busy with throughout eternity, before creating the world? The Pious Blind Man: And what follows from the fact that I would seek in vain to know what you were busy with before I had known you? God was concerned about himself, and he thought of digging a hell for those who did not believe in him, or who refused to serve him. The Unholy Blind Man: How can there be three persons in God, each of whom is God, although they are only one God? This is beyond me: madness to believe what one does not understand. The Pious Blind Man: I firmly believe that there is only one God in three truly distinct persons, who are God, and in this I do not act like a fool, but like a wise man. The Impious Blind Man: Show me this, and I will give you my staff which is very solid, and which I have been told is very beautiful. The Pious Blind Man: How do you know that your stick is beautiful? Does a blind man understand what beauty is? We blind people understand nothing about what we call colors. Who could make us understand what it is, and what difference there is between red and yellow, green and blue? Should we deny that there are colors,and that there is a difference between the colors, until we have been made to understand what it is? The Unholy Blind Man:No, because we have so many reasons to believe it, all men who are not blind say it. The Pious Blind Man: These are men who tell us that there are colors, and we believe them! It is a God who has revealed the mysteries, and we will not believe it! Don't we have much more reason to believe in the existence of the Holy Trinity and other mysteries than in the existence of colors? The Christian religion which teaches the mysteries is demonstrated to be divine, learn about it. Let us believe and live until death Christianly, we will go to heaven. As soon as we are there, we will cease to be blind. There we will see God face to face and as he is. The Holy Trinity will then no longer be a mystery.
A servant of God, who had a singular devotion to the Most Holy Trinity, said every day a certain number of times: In the name of the Father and of the Son and of the Holy Spirit. Blessed be the Holy Trinity. —Holy , Holy, Holy is the Lord . — Glory to the Father, the Son and the Holy Spirit .
(Lesson taken from the Explanation of the catechism for the use of the churches of the French empire , 1810)
taken from the excellent Catholic blog : le-petit-sacristain.blogspot.com