The saint often recalls the ineffable mystery of the Trinity in his Sermones.

They are not abstract speculations, but rather sublime elevations on the part of Brother Anthony, who emerged himself in the splendour of the trinity light in mystic contemplation and frequently burst out in songs of praise.

In the same spirit of the Church in its liturgy, at the end of each psalm he raised the minds of the faithful to the most august of the mysteries of the Christian faith. The saint, in the Sermones, and particularly in the concise eucological formulas or prayer with which he ends them, projects the thought of the believer into the intimate life of God. In his theological reflection on the Trinity, Anthony first enunciates the data and the regulations of faith, then proceeds to the demonstration of human faculties. First there is the experience of faith, which the word of revelation is essentially a part of, and then the speculation of the intellect, guided and sustained by written testimony.

With a master's touch, Anthony establishes the doctrine of the trinity here and there, with affirmations of admirable precision. Commenting on the eminently trinitary text of Mathew, "Go forth, then and teach the nations, baptise them in the name of the Father, the Son and the Holy Spirit" (28,19), the saint observes, "The Lord said "in the name" and not "in the names" to indicate the unity of the essence. With three names he teaches that they are three people. The fundamental thesis that unites and conditions the various assertions about the Trinity as a mystery, that is, the doctrine regarding the three divine people in their nature, is evidently formulated here: not a triple God, but a Trinity God."

The divine people are absolutely equal. In the Trinity, affirms Anthony, "there is no need to establish levels, so that the Father is greater than the Son and he is less than the Father, or that the Holy Spirit is less than one or the other. One must simply believe that the Father is as the Son who is as the Holy Spirit."

Anthony also shows himself to be a confident teacher when he speaks about the relationships and processions of the three divine people, when he calls for reflection, with admirable clarity and depth, on the most intimate and vital operations of the Trinity. "The highest origin," as Augustine says in his book De vera religione, "is the Father, from whom come all things and from whom proceed the Son and the Holy Spirit. Perfect beauty is represented by the Son, who is the truth of the Father, and in no way dissimilar to him. A most blessed element and the sum of good is found in the Holy Spirit, who is the reciprocal gift of the mutual love between the Father and the Son."

Revelation is the source and the point of arrival for any study of the mystery of God. Man's intelligence works on the revealed data. This intelligence knows God truly in his manifestation of himself, but with the limits of human capacity.

Man's limited effort has taken various directions and diverse paths. But they all have a common and universal principle: the participation of creatures with God's being. The similarity between God and the creatures is true and it truly teaches us something about him. This is not a "demonstration," but rather a "presentation" of the Trinity God.

Every being exists in the measure of its participation in the absolute being of God. There is, therefore, in every being created, something of God's being. All of this, unquestionably, leads to a qualitative and quantitative similarity between the absolute being, God, and the created being, the creature, that participates.

Now, the metaphysics of the divine being, as revelation teaches us, is a metaphysics in which the Trinity is not something added on or accidental. In the final reality of God, the Trinity is necessary for the measure of unity. In this necessary structure one should find a reflection, an image in all created beings whose reason for being is found in the participation with the divine being. The creature, fruit of the creative activity of the God who is One and Three, should testify in some way the source from which he comes and the model he copies.

As a matter of fact, Anthony, following in the footsteps of Saint Augustine, his favourite teacher, sees a "created trinity" in the Augustine psychological theory. He sees in the human soul a vestige, although imperfect, of the Holy Trinity. The saint turns to man's soul to try to penetrate more deeply the intelligence of the mystery of the trinity because he knows that man, in his soul, is the image of God. This is taught expressly through revelation. God made man in his image and likeness (cf. Gen 1, 26)

This prerogative, which places man above any being and first in the hierarchy of created things, is a constituent part of the human soul. Basing the knowledge of the divine mystery on knowledge of the human soul is not, therefore, an arbitrary supposition or an artificial application of a philosophical or psychological truth to the mystery of divine life. The human mind is conscious of its own existence, it has intentions and it loves itself. Considering this, we find a trinity; not exactly God, but an image of God. This sort of trinity, or memory, intellect and will or love, is not three lives, but a single life; not three souls, but a single soul; not three essences, but a single essence. Memory, intellect and will or love are three terms, each distinct from the other, but which, together, form a whole because they exist fundamentally in the spirit. The spirit, reflecting above itself, generates thoughts about itself, and from the generator as from the generated comes the third term, love. The soul, knowing itself, loves itself; in fact, it could not love itself if it did not know itself. Love is a kind of embrace that unites the generator and the generated.

This reflexive analysis teaches that memory, intellect and will are three faculties of a single and identical soul. Revelation affirms that the Father, the Son and the Holy Ghost are three distinct people in the unit of a single and same divine essence. Certainly, the mystery has not been explained, but it is attenuated in that which is could be most upsetting for the human mind.

Speaking of the Father, Saint Anthony does not emphasise his divine attributes of causality, omnipotence, or infinity, but rather he underlines His goodness and His mercy. The word "Father" is intimately associated in the saint's mind with a loving God, who saves His creatures, who gives of himself to them. God the Father is love, writes Anthony; only He can communicate that what He is, love, as long as we ask him in our prayers in the name of Christ. The Father is Supreme Good, who extends to all existing creatures His kindness. Everything that is above Earth, in the air, in the water, everything that is in the sky and among the angels, everything that has intelligence and reason, lives, moves and exists; all of this comes from Him, universal principle and fountain of goodness.

Between God and man there is a big difference: man involves himself in deeds to acquire something and to increase his own happiness; God, who has everything, acts externally only to give. When an imperfect being gives, it can not put itself aside; even in his most generous outbursts of affection, man is a bit selfish. Only God, the Most Perfect, the "fountain of goodness," works freely for pure love.

Saint Anthony often speaks of the mercy of the Father, to instil confidence in the repentant sinner. He calls Him by the name of "Father of Mercy" because he connects Him especially with the attribute of mercy. He who one day wishes to participate in the joy of the heavenly banquet should consider the power of the Lord, the wisdom of God, the mercy of the Father; consider His power in fear, his wisdom for knowledge and his mercy to confide.

The Father can be known adequately if He is contemplated in the face of the Son, who is the full revelation of His love down here in the world. Anthony, in calling Christ Verbum Patris, Sermo Patris, Vox Patris, more than giving an ontological sense of the divine derivation of the Word, wants to point out the very close relationship between the Father and the Son in the history of salvation, a history that reveals the love and mercy of the Father. In the Sermones, the saint develops a functional theology, more that a theology of being.