As evangelists and catechists, our number one job as catechumenate ministers is to bring people into intimacy and communion with Jesus Christ. That is impossible to do if we do not fully comprehend and teach that Jesus is part of a Holy Trinity.

The Catechism of the Catholic Church says that the truth of the Holy Trinity is at the very root of Christian living. That means that the mystery of the Trinity is not an esoteric philosophy for masters-level theology students. It is a lifestyle template for every Christian—from the youngest child to the eldest grandparents.

How the early church learned about “Trinity”

There is a misconception that the mystery of the Trinity is difficult to understand and therefore difficult to teach. We have to get past that. The “mystery” is no mystery in the sense of a puzzle. It is a mystery in the same way love is a mystery. We all understand love. The mystery of love is that it is a paradox—the more we give of ourselves to another, the more we receive; the more we unite ourselves to another, the more we become our true self. The Trinity is a mystery in the very same way.

But this understanding about the Trinity didn’t just come fully-formed from out of the sky. The early Christians had to reflect back on their relationship with Jesus the meaning of his resurrection.

From these reflections, they realized that Jesus is the Christ or Messiah. They also realized that Jesus is Lord. A huge insight they got was that Jesus is the Word made flesh. And another was that Jesus is the Son of God. These are all things that became clearer to the church after the Resurrection.

Yet they also knew there could only be one God. So if Jesus is the Son of God—and also God—did that mean there are two Gods? For us in the 21^st century, the answer is very clear, but our early ancestors in faith struggled with this dilemma for over 100 years. What was at stake was not merely a theological idea. The answer to this problem would determine who Christ was and what his relationship to us would be.

One person who tried to uphold the understanding that we worship one God alone was a priest in Egypt named Arius. He taught that God the Father created the Son and that there was a time when the Son was not. This meant that the Son was subordinate to the Father. It also meant that the Son was not God by nature, nor was he of the same essence as the Father.

However, Athanasius, the bishop of Alexandria, Egypt, had a bone to pick with Arius. Bishop Athanasius said that only God could save. And the way God saves us is by giving us a “share in the divine nature” (2 Peter 1:4). Therefore, if Christ saves us, then Christ is God—not a go-between, not a subordinate, but true God from true God.

The debate between Arius and Athanasius became so controversial that it threatened the unity of the Roman empire. So Constantine, the Roman emperor, called a council of all the bishops from all over the empire to settle the matter. That council was held in 325 in Nicea, from which we derive the Nicene Creed. Athanasius won the day, and so in the Creed, we say that the Son is one in being with the Father. Or in the new translation, we say that the Son is “consubstantial” (of one substance or essence) with the Father.

There is a misconception that the mystery of the Trinity is difficult to understand and therefore difficult to teach. We have to get past that.

A love story

Yet all this still seems a bit academic. Where does the mystery of love come in?

The Eastern church can help us with this. Their insight is that the Trinity is an action we participate in. It is a dance between lovers so intimately bound to one another that if they stopped loving each other, they would lose their identity. And all creation is caught up into their dance and re-shaped into the deep mystery of their love.

To understand the Trinity then, we need look no further than our most intimate relationship with another person. Every time we give when we have nothing left, every time we forgive when there is no reason to—that is the mystery of the Trinity. It’s the human capacity to love and hope and create despite an unknown future.

From mystery to math

It was important at the time of Arius and Athanasius to come up with a very precise phrasing of what the church believes about Jesus so we could stop arguing and get back to worshipping as one, unified community of faith. However, we also paid a price for that.

Over the centuries, the theology of the Trinity became a specialty for those with deep theological training. For ordinary Christians, it became a complex math problem that my third-grade teacher summed up for as “a mystery that will be revealed to us in heaven.”

However, we cannot leave it at that. The mystery of the Trinity is not about math; it is about relationship. If we are going to have an intimate relationship with Jesus, and if Jesus is “consubstantial” with the Father, that means that we are also in an intimate relationship with the Father. We also have to understand that it is only through Jesus—through the Spirit of Jesus—that we are able to be reconciled to and become one with the Father.

This is the very heart of Jesus mission. It is not a mystery that will be revealed to us after we die. Jesus is the revelation, here and now.

The mystery of the Trinity is not about math; it is about relationship. If we are going to have an intimate relationship with Jesus, and if Jesus is “consubstantial” with the Father, that means that we are also in an intimate relationship with the Father.

God is love

As we are catechizing the catechumens and candidates, it is less important to focus on the math of the Trinity and more important to focus on the why. Why would God go to all the trouble of creating the world, creating us, and then sending the Son to save us? We arrive at the same answer as the early disciples. God is love. “God has no other reason for creating than his love and goodness: ‘Creatures came into existence when the key of love opened his hand’” (Catechism of the Catholic Church, 293). That is the mystery of the Trinity.