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Text: Acts 2:14a, 22–36
Liturgical Date: Holy Trinity (C)
Calendar Date: June 16, 2025

Location: Saint Peter’s Lutheran Church in Door County; [Address] 316 W Main St, Forestville, WI 54213; [Phone] (920) 856-6420
Preacher: Rev. Dr. Christopher D. Jackson

Saint Peter’s Lutheran Church in Door County serves Sturgeon Bay and other areas in Door County, Kewaunee County, and Brown County.

TRANSCRIPT

Note, the following transcript was created with the assistance of AI and does not match what was preached word for word.

Holy Trinity Sunday Sermon

In the name of the Father and of the Son and of the Holy Spirit. Amen. Today, on this Holy Trinity Sunday, we celebrate with great thanksgiving the knowledge of God as Father, Son, and Holy Spirit. Three divine persons in one God, and one God in three divine persons. We will be talking about that at length as we go along.

The Importance of Christian Fatherhood

But even as we talk about our Heavenly Father, I would like to take a moment to talk about fatherhood on this Father’s Day weekend. Fatherhood is incredibly powerful, though it’s a power that is probably downplayed in our society right now. The greatest thing that fathers can offer is oftentimes overlooked.

This weekend, my mind is on a man I never met—my great-grandfather. Why is my mind on my great-grandfather? Well, I just had the great privilege to fly out to Colorado for my nephew’s baptism and to see my grandmother, Ruth McGhghy, whose maiden name was Helms. She’s 97 years old, a lovely Christian lady. Her Christian prayers and example are very powerful. I don’t think you would have a pastor standing here if it were not for her Christian virtue, prayers, and example. She was a Lutheran pastor’s wife and help to hold up the hands of the prophet, as it were—my grandfather, Hugh. She helped raise a young man who became a Lutheran pastor, my uncle, Paul McGhghy, and then there’s myself.

How did she come to have such a firm Christian faith, so deeply held? When you talk to Ruth about her upbringing, she comes back time and again to the centrality of faith in the household she was brought up in. There’s one person she always mentions as having a central role in that faith, and that was her father. He was a man many in this world would probably look down on. He was rather unsuccessful in the eyes of the world. He was a farmer, but instead of being a smart farmer like those who farm land around here, he was a dumb farmer because he chose land not meant to be farmed out in western Nebraska. He tried to farm that land, as many others did. You know the land here throws up stones every winter, but once you pick up those stones, it’s pretty fertile, and there’s lots of moisture. In Nebraska, where I’ve visited the ancestral lands in Arapahoe, it’s sandy and doesn’t get much rain. It’s basically desert. When I’ve gone to the Emmanuel Lutheran Cemetery, where my forebears are buried, there are honest-to-goodness cacti growing on the ground. That’s the land he tried to farm. My family that still lives there converted to ranching long ago—that was the right call; farming was a bad idea.

When you got to be 18 and were one of his daughters, you got two presents: a suitcase and a ticket to North Platte, the big city, where Ruth met the choir director at the Lutheran church. Even though she had to send back her hard-earned money to the family farm to help support her parents, she always talks about her father with deep reverence because of the faith he taught her. I grew up for about six years in the Plains states, and every week in the springtime, we’d go down to our basement because of the tornadoes swirling out on the plains. She had to do the same. When her father took them down into the basement, he’d have a lantern in one hand to give light and, in the other, a devotional book common in Lutheran households at the time, called The Family Altar. It contained prayers, hymns, Bible readings, and devotions. He read these to his children to calm them as the tornadoes swirled around. He relied on their faith not only in times of trouble, when they worried about tornadoes leveling their house, but also on a daily basis. At the three meals a day they ate together as a family, he led his 12 children in prayers. Ruth recalls with great fondness a simple prayer she was taught as one of the youngest: “Abba, beloved Father, amen.” I’ve heard some old-timers around here say they were taught this prayer as well.

That man left almost nothing of a worldly legacy but an immense spiritual legacy. That’s my encouragement to the fathers of this congregation and those who would be fathers, even if your children are grown. It’s not too late to start telling those the Lord has entrusted to you about Christ Jesus, what He has done for them, and to teach them to pray and acknowledge that, while you are an earthly father, they have a Heavenly Father who looks after them, loves them, and cares for them.

Fatherhood is vital, and fathers aren’t interchangeable. You don’t honor any random dad on Father’s Day; you honor your dad. So it is with our God. We don’t honor any random father in heaven but the one true Father. We worship only one true God—Father, Son, and Holy Spirit—forsaking every other false god who would seek to lead our hearts astray.

This is a big part of why we mark Holy Trinity Sunday and why it matters. Our sermon today has three points. First, we’re talking about why the doctrine of the Holy Trinity matters. Second, what is our belief in the Holy Trinity? And finally, our belief in the Trinity stands upon our conviction that Jesus is the eternal Son of God and equal with the Father.

Why the Doctrine of the Holy Trinity Matters

As I mentioned, on Father’s Day, we don’t honor just any random father; we honor our fathers. In like manner, the object of our love as Christians is the only true God—Father, Son, and Holy Spirit. This is why we mark Holy Trinity Sunday: because the identity of God matters. We do not love interchangeable gods. We reject all false gods, as commanded in the First Commandment: “You shall have no other gods before me.” This means we should fear, love, and trust in God above all things, forsaking any false gods or goddesses, including those of this world that seek to allure us astray, like wealth and fame.

Second, if God is not triune, we are still dead in our sins. If Jesus were not God, the eternal Son of God, we’d have no assurance that His sacrifice covers our sins. If He was a mere man, maybe He could give His life for one other. If an angel, perhaps for many. But because He is God, He gave His life for the sake of all. His sacrifice is of infinite merit, so we know He died for us. That sacrifice was offered to the Father, the Judge of all, as Jesus commended His spirit to Him. This gift must be received by faith. While Christ died for all, not all receive the benefit because not all believe. But those who believe have hearts transformed—a true miracle, something only God can do. Just as God creates something out of nothing, as we read in Proverbs 8, the Holy Spirit transforms our cold, dead hearts into hearts that trust in the Lord and the benefits Christ won through His death and resurrection.

Finally, it matters because we are called to love, serve, and obey the one true God—Father, Son, and Holy Spirit.

What We Believe About the Holy Trinity

The word “Trinity” comes from “tri” (three) and “unus” (one), summarizing our belief: God is Father, Son, and Holy Spirit—three eternal persons and one God. We believe the Father is God, the Son is God, and the Holy Spirit is God, yet there are not three gods but one God. The three persons are distinct, eternally existing, with an eternal relation to one another.

This helps us identify false teachings. One common error is modalism, which says God puts on a costume—sometimes as the Father, sometimes the Son, sometimes the Holy Spirit. This is common among Pentecostals and even appears on the “What We Believe” pages of some LCMS churches, though it contradicts our confessions. Another false teaching is Arianism, the belief that the Son is not eternally equal with the Father but was elevated to the status of God. This is taught by Jehovah’s Witnesses, Mormons, and others. If anyone says the Son is anything less than fully and eternally God, they are teaching false doctrine, and we must reject it.

Jesus: The Eternal Son of God

Our belief in the Trinity stands upon our conviction that Jesus is God, equal with the Father. We saw this in today’s readings. In John 8, Jesus expresses that He is God, noting that all prophets before Him died, but His resurrection shows He is true God. In Acts 2, Peter says of the patriarch David, “He both died and was buried, and his tomb is with us to this day. Being a prophet and knowing that God had sworn with an oath to him that He would set one of his descendants on the throne, he foresaw and spoke about the resurrection of the Christ, that He was not abandoned to Hades, nor did His flesh see corruption. This Jesus God raised up, and of that we are all witnesses, being therefore exalted at the right hand of God.” Peter speaks of the resurrection and ascension, noting that David did not ascend into the heavens, but Jesus did, fulfilling the prophecy: “The Lord said to my Lord, ‘Sit at my right hand until I make your enemies your footstool.’”

Peter emphasizes that every other prophet, even great ones like David, lies dead in the ground. So do false prophets like Buddha, Muhammad, and Joseph Smith. They were not the Son of God. But Jesus rose; there is an empty grave in Jerusalem. Through His resurrection, He demonstrated He is no mere man or prophet but the Son of God. He ascended to the Father’s right hand, where no mere man can sit. He is both God and man.

Jesus commended His spirit to the Father, promised the Holy Spirit, and commanded us to make disciples by baptizing in the name of the Father, Son, and Holy Spirit. We believe in the Holy Trinity because it is the doctrine taught clearly by Jesus Christ, whom we are convinced is God.

This is why the incarnation of Jesus as the Son of God is intimately connected to the doctrine of the Holy Trinity. The Athanasian Creed, found on page 319 in our hymnals, has two parts: verses 1–26 discuss the eternal relation of Father, Son, and Holy Spirit, while verses 27–40 address the incarnation of the Son in human flesh as Jesus of Nazareth. The creed uses the term “Catholic,” meaning universal, to confess our shared faith, which finds its fullest expression in the Lutheran Church. At verse 39, it says, “Those who have done good will enter eternal life, and those who have done evil into eternal fire.” This is not works-righteousness but reflects Christ’s words in Matthew 25, that those made good through Christ’s righteousness do deeds pleasing to God and enter eternal life.

As we confess the Athanasian Creed, we affirm our confidence in the divinity of Christ and the doctrine of the Holy Trinity. May we pass on this faith, trusting in the one true God—Father, Son, and Holy Spirit. Amen.