Holy Trinity Sunday, the first Sunday after Pentecost in the church calendar, turns many Christians into mini detectives. Magnifying glasses in hand, they twist themselves into knots trying to unravel and explain the mystery of the triune God without wandering into heresy.

In his Prayer Book, Johann Friedrich Starck compares trying to understand this deep mystery of the Trinity, how He can be both three persons yet one God, to staring at the sun.

“When believers are about to begin a meditation on the mystery of the Holy Trinity, they must be like those who want to obtain the light and benefit from the sun and make it serve them. If they look into the sun with unprotected eyes, they become blinded; they see nothing but darkness, indeed, nothing at all. But if they keep their eyes cast down and thus use the light and splendor of the sun, they see much. Indeed, they see all that they ought to see” (p. 108).

Scripture doesn’t explain the mysterious way God is three in one, only that He is God the Father, God the Son, and God the Holy Spirit. When we try to understand this mystery with our finite abilities, we end up blind. It’s too great and too brilliant a mystery to see. And, if we obsess over this mystery, always looking up, we’ll remain blind to the work of God around us.

But if we want to “obtain the light and benefit” from it, we need to look to what is illuminated, as Starck suggests. On Holy Trinity Sunday, God draws our attention, not to the inner workings of the Trinity, but the outer workings of God the Father, Son, and Holy Spirit. Those things we can see; namely, the work of the triune God for us.

For us, God the Father sent His Son. Not to condemn us, but to save us by His death and resurrection (John 3:17). In doing so, the Son reveals to us the loving and gracious nature of the Father toward us (Matt. 11:27). The Father, in turn, glorifies the Son (John 8:54). Both the Father and the Son send the Holy Spirit to create and sustain in us saving faith in Jesus’ death and resurrection for us. (John 14:16–17; John 15:26). The Spirit does this by pointing us back to the person and work of Christ (John 16:13–15).

On Holy Trinity Sunday, God draws our attention, not to the inner workings of the Trinity, but the outer workings of God the Father, Son, and Holy Spirit.

God doesn’t ask us to look into the light, to ascend to Him in our understanding. Instead, He sheds light on the mystery for us by condescending to us in His Son’s incarnation. And He descends to us in His Holy Spirit, who shines divine light on the Divine Light, a light no darkness can overcome (John 1:5). By the death and resurrection of the Son, we “who sit in darkness and in the shadow of death” see the forgiveness of our sins and our salvation most clearly and fully (Luke 1:79).

God unites us to the death and resurrection of His Son, delivering to us forgiveness, life, and salvation by putting His divine name on us in the waters of baptism (Romans 6; Matthew 28:18). As Philip Melanchthon writes, “The person who is baptized should understand that his sins are forgiven him by God himself, Father, Son, and Holy Spirit” (p. 171).

We are reminded of this work of the triune God on our behalf in the Invocation, the opening words of the liturgy. “In the name of the Father, and of the Son, and of the Holy Spirit.” They draw us back to our baptism where the Trinity works for us, for our forgiveness, life, and salvation. As Luther adds in his Large Catechism, “For to be baptized in the name of God is to be baptized not by men but by God Himself. Therefore, although it is performed by human hands, it is still truly God’s own work” (p. 129).

Again, God’s name is put on us in the Benediction, the closing words of the liturgy. “The Lord bless you and keep you; the Lord make his face to shine upon you and be gracious to you; the Lord look upon you with favor and give you peace. In the name of the Father, and of the Son, and of the Holy Spirit.” These words come from God’s command to the priests to bless His people, “So shall they put my name upon the people of Israel, and I will bless them” (Numbers 6:23-27).

God the Father, Son, and Holy Spirit work for us and our eternal benefit, not because of any merit or worthiness in us, but out of divine goodness, love, and mercy.