In dozens of places in her Diary Sister Faustina wrote about the Holy Trinity, but let’s survey just a few of the principal ones here.
First of all, she says that as she advanced in her journey with Jesus Christ and came to appreciate more deeply the compassion of His Heart, “His Trinitarian Being enveloped me entirely” (Diary, 1056). In other words, the more she grew closer to Jesus, the more she felt enveloped in the Holy Trinity. For example, on the Feast of the Ascension, 1937, she wrote:
After Holy Communion I communed for a while with the heavenly Father. My soul was drawn into the glowing center of love. I understood that no exterior works could stand comparison with the pure love of God. … I saw the joy of the Incarnate Word, and I was immersed in the Divine Trinity. When I came to myself, longing filled my soul, and I yearned to be united with God (Diary, 1121).
Notice in the last quote how she connects a deeper appreciation for the Trinitarian mystery of God with an appreciation of the “glowing center of love” in God. We find this again in entry 1020:
I understand the spiritual espousal of a soul with God, which has no exterior manifestation. It is a purely interior act between the soul and God. This grace has drawn me into the very burning center of God’s love. I have come to understand His Trinitarian quality and the absolute Oneness of His Being.
Often she received a deeper understanding of the Blessed Trinity during the celebration of the Holy Eucharist. For example, in entry 472 she tells how one time she heard an angel singing “Holy, Holy, Holy” at the moment of the elevation of the Host, and then she received new light into the mystery of the Trinity:
I knew more distinctly than ever before the Three Divine Persons, the Father, the Son, and the Holy Spirit. But their being, their equality, and their majesty are one. My soul is in communion with these Three; but I do not know how to express this in words; yet my soul understands this well. Whoever is united to One of the Three Persons is thereby united to the whole Blessed Trinity, for this Oneness is indivisible (472).
Once after Holy Communion, I heard these words: You are our dwelling place. At that moment I felt in my soul the presence of the Holy Trinity, the Father, the Son, and the Holy Spirit. I felt that I was the Temple of God. I felt that I was a child of the Father. I cannot explain all this, but the Spirit understands this well (451).
Sister Faustina even tells us that in heaven the souls of the saints forever contemplate the wonder of the Holy Trinity:
Today I was in heaven, in spirit, and I saw its inconceivable beauties and the happiness that awaits us after death. I saw how all creatures give ceaseless praise and glory to God. I saw how great is happiness in God, which spreads to all creatures making them happy; and then all the glory and praise which springs from this happiness returns to its source; and they enter into the depths of God, contemplating the inner life of God, the Father, the Son, and the Holy Spirit, whom they will never comprehend nor fathom.
This source of happiness is unchanging in its essence, but it is always new, gushing forth happiness for all creatures. Now I understand St. Paul who said, “Eye has not seen, not has ear heard, nor has it entered into the heart of man what God has prepared for those who love Him” (777).
Now, you might be thinking to yourself, “That is all very beautiful, but I still don’t get it! What does the Trinity really mean? How can God be One in being and essence, but Three Persons at the same time? And what difference does it really make if we believe all this or not?”
Well, Sr. Faustina wanted to know more, too! Listen to what she wrote near the very start of her Diary:
On one occasion I was reflecting on the Holy Trinity, on the essence of God. I absolutely wanted to know and fathom who God is. … In an instant my spirit was caught up into what seemed to be the next world. I saw an inaccessible light, and in this light what appeared like three sources of light that I could not understand. And out of this light came words in the form of lightning which encircled heaven and earth. Not understanding anything, I was very sad. Suddenly, from this sea of inaccessible light came our dearly beloved Savior, unutterably beautiful with His shining Wounds. And from this light there came a voice which said, Who God is in His Essence, no one will fathom, neither the mind of angels nor of man. Jesus said to me, Get to know God by contemplating His attributes. A moment later, He traced the sign of the cross with His hand and vanished (30).
So, right from the start, Jesus was telling her that no one can ever completely fathom the mystery of the Trinitarian Being of God, but that if we contemplate God’s attributes, we can at least begin to understand it. And as we have seen, that is precisely what Sr. Faustina did: The more she contemplated the compassionate love in the Heart of Jesus, and the more she appreciated the “glowing center of love” in God and the “burning center of God’s love,” especially manifested in the Holy Eucharist, the more she began to appreciate what it means to say that God is Three Persons in One Being or Essence. She tells us the same thing in her extended meditation on the Trinity in entry 911:
On one occasion God’s presence pervaded my whole being and my mind was mysteriously enlightened in respect to His Essence. He allowed me to understand His interior life. In spirit I saw the Three Divine Persons; none of them is either greater or smaller; there is no difference in either beauty or sanctity, for They are One. They are absolutely One. His Love transported me into this knowledge and united me with Himself. When I was united to One, I was equally united to the Second and to the Third in such a way that when we are united with One, by that very fact, we are equally united to the Two Persons in the same way as with the One. Their will is One, One God though in Three Persons. When One of the Three Persons communicates with a soul, by the power of that one will, it finds itself united with the Three Persons and is inundated in the happiness flowing from the Most Holy Trinity, the same happiness that nourishes the saints. This same happiness that streams from the Most Holy Trinity makes all creation happy; from it springs that life which vivifies and bestows all life which takes its beginning from Him. In these moments, my soul experienced such great delights that I find this difficult to express.
Sr. Faustina was actually given the key that unlocks for us the mystery of the Trinity. Not only is the Trinity entirely true and justifiable on the basis of logic and of Scripture, but in the light of Divine Love, it begins to make sense of the mystery of God Himself.
After Holy Communion I communicated for a while with the heavenly Father. My soul was drawn into the glowing center of love. I understood that no exterior works could stand comparison with the pure love of God. … I saw the joy of the Incarnate word, and I was immersed in the Divine Trinity. When I came to myself, longing filled my soul, and I yearned to be united with God. …
I understood the spiritual espousal of a soul with God, which has no exterior manifestation. It is a purely interior act between the soul and God. This grace has drawn me into the very burning center of God’s love. I have come to understand His Trinitarian quality and the absolute Oneness of His Being.
~from the Diary of St. Faustina, 1121
According to Scripture and Sacred Tradition, God must not be seen as a solitary heavenly being, as if sitting alone on the heavenly throne by Himself. In St. John’s vision of the heavenly Kingdom, recorded in the last chapter of the Bible, he sees “the water of life, bright as crystal, flowing from the throne of God and of the Lamb” (Rev 22:1), in other words, the Spirit of God flowing eternally from the Father and the Son.
Thus, God’s own inner life, in a mysterious way, is Tripersonal. God is not a solitary person. Rather, from all eternity, from everlasting to everlasting, before He ever made the universe, and even if He had never made any universe at all, God already knew what it was like to love; in fact, He already enjoyed the fullness of perfect love — love given, love received, and love returned — within His own divine nature. As St. John wrote: “God is love” (1 Jn 4:7). “Love” is what God is by definition; in other words, perfect Love is going on within the divine nature all the time. It is not something God just chooses to do now and then. In His own eternal, infinite Being, therefore, God was never one solitary person, but always Three divine Persons — Father, Son, and Holy Spirit — united forever in mutual, self-giving love.
As C.S. Lewis once wrote, their unity is like the unity among dancers who are moving to the same song in perfect harmony and perfect self-giving. Even so, the Three Persons share eternal joys, cooperate in divine purposes, and manifest together every divine perfection: an eternal dance of love among the Persons of the Blessed Trinity.
If God is a Holy Trinity defined in this way — a Trinity of eternal, perfect love — then this doctrine also tells us something important about why God created the world. He obviously did not create the world because He needed to, as if to cure Himself of His own loneliness, or to fulfill some unrealized potential in His own nature for loving relationship. God didn’t need to do any such thing, for He already knew what loving personal relationship was like — love given, love received, and love returned.
God already enjoyed the perfect fulfillment of loving relationship within His own nature, in the Trinity. Then if God did not need to create us, why did He do so? It can only be because He wanted to share His perfect love with creatures: He wanted to create beings who could take part, each one in its own way, in His perfect divine love, and enjoy it by joining in the dance!
Other religious faiths (such as Judaism and Islam) share our belief that there is One God. But what they fail to see is that if God is, as they hold, one single divine Person, then He cannot be said to have the attribute of perfect Love. For before such a God made the world, and apart from His relationship with the world, He would not have known the joy and perfection of loving personal relationship. Thus, in Himself, such a God could not be called the God of Love; He would only be “potentially loving,” for He would need to create a world in order to have something or someone to love. And even in His love relationship with the world, such a God would never know the perfect joy of having His love fully received and fully returned, something that finite creatures, even the best of them, could never do. Only divine Persons can fully receive infinite divine Love, and infinitely return it. In short, a unipersonal God would be a “needy” God: a divine being who created the world in order to fulfill His own potentials for loving personal relationship, and never quite succeeded. This hardly matches the Biblical witness to the infinite majesty, glory, and holiness of God!
On the other hand, if, as Christianity teaches, from everlasting to everlasting God is perfect Love within Himself, if He enjoys the perfection of personal relationship within His own eternal Being, if He is not one solitary person but Three Divine Persons united in self-giving love and sharing all the divine perfections, then it follows that God did not create us out of any selfish need of His own, but out of selfless generosity: out of an overflow, so to speak, of His Trinitarian love. He created us so that we might one day share in the same interpersonal love that makes up His own eternal joy. For it is the same divine love that eternally binds the Three into One, and it is the same Trinitarian Love that called us into being and invites us now to join in the dance.
Perhaps now we can begin to understand what St. Faustina meant when she wrote that coming to know the secret of the Trinity involves being “drawn into the glowing center of love,” when one is “immersed in the Divine Trinity.” But, she also added: “I do not know how to express this in words.”