Trinity Sunday: a preacher's nightmare

Trinity Sunday, year B
Trinity Sunday has often been called a “ preacher’s nightmare”.  What can we possibly say about the Trinity, the single greatest mystery of our faith? When we do pluck up the courage to say something about the Trinity, we easily risk falling into some heresy or another. Though I feel some of this pressure, I personally enjoy preaching on Trinity Sunday for one simple reason: I am a nerd. My preaching professor always told us that we should keep our homilies practical and down to earth. We were told to avoid Churchy and theological talk. But today, Trinity Sunday, is an exception. Today we get to be nerds! So let’s talk Trinity theology today.


If we want to talk about the Trinity we need to start with Jesus. Though you will not find the word “Trinity” in the Bible, it is Jesus who revealed to us this belief. During His ministry, Jesus was clear that He had been sent by the Father. This assertion did not differentiate Him from any other prophet like Moses or Isaiah. Jesus, however, went further. With His words and actions He claimed to be God. He forgave sins, something only God could do. He felt at liberty to add to the Law. God alone is the lawgiver. He said that He and the Father are one. After His Ascension, Jesus promised that He and the Father would send the Holy Spirit, who was not just a gift from God but was in fact God Himself. During His life, therefore, Jesus revealed to us our belief in the Trinity: God is only one, but He exists in three persons, Father, Son and Holy Spirit.


Jesus’ revelation of the Trinity, which we take for granted today, was extremely controversial among His contemporaries. His words were met with confusion and open hostility. For Jews, the single most important thing that they believed was that God is one. This is expressed in the Shema, the famous Jewish credal formula:
Hear, O Israel: The LORD our God, the Lord is one. And thou shalt love the LORD they God with all thy heart, and with all thy soul, and with all thy might. (Deut 6:4-5)
1st century Jews were their guard against any teaching that took away from the unity of God. Jesus’ words would have seemed like blasphemy to them.


For this reason, early Christians - most of whom were Jews - struggled to comprehend the Trinity. How could God be one and three? Reflection on this is already present in the New Testament. An incredible insight into this mystery is found in 1 John: God is love (1 John 4:8). It does not say that God, like us, loves or is lovable, but that He is love. From all eternity, before anything was even created, God is love. In order for God to be love, we should find in God, and in fact do find, a communion of persons: lover (Father), beloved (Son) and bond of love (Holy Spirit).


After the New Testament came into being, the greatest minds of the Church continued grappling with the mystery of the Trinity. St. Augustine of Hippo came up with one of the most helpful ways to understand this mystery, something we call the Psychological Analogy for the Trinity. Augustine’s starting point is how we are built as human beings. Since we are created in God’s image, we can learn about who God is by observing human nature. As human beings, we have two main abilities: thinking and loving. We find that every human being is able to create a mental image of himself or herself. We do this whenever we try to answer the question “who am I”? In answering this question, you create an idea of who you are. What you look like. How you speak. How you act. Though we may not be happy with all its aspects, hopefully on the whole we love this self image. After all, Jesus calls us to “love your neighbour as yourself” (Mark 12:31). We are all, therefore, able to both create a mental image of ourselves and also to love this image. Augustine explains that when we consider God doing the same thing, we better understand how the Trinity arises. When God the Father thinks about Himself, His self-image is so perfect that it is not just an idea but actually a person, God the Son. God the Father, aware of this image of Himself, loves it perfectly. This perfect love is the Holy Spirit. We can therefore understand the Trinity by considering God thinking about and loving Himself.The Son comes about when God the Father thinks about Himself. The Holy Spirit comes about when the Father loves the Son, His perfect self image.


For over 300 years the Church discussed and struggled to comprehend the mystery of the Trinity. During this time, individuals often made mistakes in trying to explain the Trinity. Some would overemphasize the unity of God, neglecting that God is three persons. Others would overemphasize that God is three persons, downplaying the unity of God. Perhaps the greatest challenge to our belief in the Trinity came about in the fourth century. At this time, the teaching of a particular priest from Alexandria named Arius became very popular. In order to protect the fact that God is one, Arius downplayed the Divinity of the Son. Arius claimed the Son was not the same nature as the Father. The Son was the first of all creatures, ranking high above any other created thing. He was worthy of great respect, yet He was not God. This teaching of Arius became very popular and many Bishops believed it. It threatened to tear the Church apart. In order to head off the problem, the Emperor Constantine called a council in order to settle the matter. This council was held in Nicaea in the year 325. There, the Bishops of the Church resoundingly denounced the teaching of Arius, affirming that Jesus was indeed God. If Jesus was not God, His death on the Cross could not save us. The Council of Constantinople in 381 later reaffirmed the Divinity of the Holy Spirit. From these two great councils we derive one of the creeds we say at Mass, often called the Nicene Creed. The language of this creed defends our belief that Jesus is indeed God, one of the persons of the Trinity:
I believe in one Lord Jesus Christ,
the Only Begotten Son of God,
born of the Father before all ages.
God from God, Light from Light,
true God from true God,
begotten, not made, consubstantial with the Father;
through him all things were made.
Thanks to the Councils of Nicaea and Constantinople, our belief that the one God exists in three persons was defended.


We may be tempted to think that the doctrine of the Trinity has no practical application to our life. It is a discussion for Catholic nerds alone. Nothing, however, could be further from the fact. We believe that we are made in the image of the Trinity. Therefore, in order to understand how we are to live as human beings, we must understand the Trinity. Here are just a few of the practical consequences of our belief in the Trinity.
  • The Trinity is our origin and our final destination. We have been created out of the overflow of love in the Trinity. The end goal of our life in union with the Trinity.
  • In our culture we place a great value on independence and on self sufficiency. God however, is not self sufficient nor forever on His own. God is a communion of persons united in a perfect relationship of love. We, therefore, are built to live in relationship with others, being interdependent on them. We are not truly human unless we are in loving relationships with others.
  • In a special way, the family forms an image of the Trinity. Just as the love between Father and Son bring forth the Holy Spirit, the love between husband and wife becomes fruitful in the generation of children.
  • In our spiritual life, we are able to relate in a personal way to each of the three persons of the Trinity, Father, Son and Holy Spirit.

We cannot possibly overstate how central the Trinity is to our life. In addition to being theology nerds for a Sunday, Trinity Sunday is an opportunity to remind ourselves of this truth that we too easily forget. Everyday we make the sign of the Cross, an expression of our belief in a Triune God. Often we do this carelessly. When you make the sign of the Cross today, take a moment to pay reverence to the great mystery of the Holy Trinity.