Sermon on Matthew 28:16-20, for Holy Trinity Sunday 2020 (A), "Theology of the Trinity"

Grace, mercy, and peace to you from God our Father and from our Lord and Savior Jesus Christ. Today is Holy Trinity Sunday, a Sunday uniquely devoted to a particular doctrine or theology—not an event in Jesus’ life, or a person, or one of God’s saving acts. But many people have no time for theology. “Abstract philosophical stuff for the libraries and ivory tower! Sounds too much like textbooks and information!” And if theology is cut off from the Living Word of God and turned into an empty pursuit, it can become sterile. But I will strive to show today how the theology of the Trinity flows from the Living Word of God and has direct relevance for our daily Christian life.

So what does an average Christian need theology for? Isn’t that just for pastors and professors? Let me ask the question differently. Does the Bible speak to our everyday life and how we live? Does it have anything to teach us about life? Does God intend for the average Christian to study the Bible? And if so, aren’t all those things theology?

Let’s consider from another angle. You know what biology is, right? The study of life. Geology is the study of rocks. Zoology: the study of animals. Cardiology: the study of the heart. Now of course, you don’t need to know all of those fields of knowledge. They don’t all have direct impact on your daily life—though we certainly benefit from the knowledge that doctors have of biology and cardiology. But following the analogy, what is theology? The study of God. The question I am really asking is do you as an average Christian need to study God (and His Word) in your everyday life? Is it important for you to know who God is and what He has done for you? The answer should be a resounding yes! You don’t all need to be experts who can lecture for days on the books of Genesis, Isaiah, or Romans—but you should above all desire to know the God who knows and loves you!

One of the most important verses in the Old Testament became the Jewish Creed. It’s called the “Shema.” “Hear O Israel, the Lord our God, the Lord is one. You shall love the Lord your God with all your heart and with all your soul and with all your might. And these words that I command you shall be on your heart. You shall teach them diligently to your children and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise. You shall bind them as a sign on your hand, and they shall be as frontlets between your eyes. You shall write them on the doorposts of your house and on your gates.” (Deuteronomy 6:4-9). Jesus called this God’s greatest command—to love God with all your heart, soul, mind and strength. God is very intent that we have his words on our heart and teach them faithfully to the next generation. That hasn’t changed in the New Testament. Jesus says in Matthew 28:20 that disciples are to be taught everything He has commanded. That’s theology. To study God and what He commands.

God wants all His children to know Him and His commands. To teach our children diligently, means to take this seriously and be committed. Parents today are very diligent about seeing that their kids follow through on sports practices, training, and drills. Success in sports means dedication and consistency. It’s no less true for passing on our faith and values. It takes dedication, consistency, intentionality. God told the Israelites to talk about His commands when sitting at home, walking, going to sleep and rising. Even marking their hands, forehead, and entrances with reminders! Some orthodox Jews follow this literally, with little boxes of scripture verses or wrappings on their arm to serve as a reminder of God. Sometimes literal reminders are best. A household sign: “As for me and my house, we will serve the Lord” or other Scriptural reminders. A cross necklace or other physical reminders in our car or at our desk catch our attention when the world seizes our flesh. When anger, frustration, or temptation arises, reminders for our eyes are good. Just don’t be superstitious about it. Objects may remind, but they won’t save or protect you. Most important is to have His words on our heart.

For you, everyday Christian—to be a theologian is no more or less than to be a student of God’s Word. To be a lifelong learner about God. How do I live under the grace and love of God? What does it mean to be loved by Him; made by Him; saved by Him? How are we set apart by Him for a holy purpose? These questions invite God’s Word to sink into your life and accomplish God’s purpose. His Living Word will change you! Let’s look at some specifics of how the theology of the Trinity answers some of these questions.

Jesus’ Great Commission was one command with two parts. The one command: make disciples of all nations. The two parts? Baptizing and teaching. Baptizing in the Name of the Father, and of the Son, and of the Holy Spirit. (That’s the Trinity!) And teaching everything that Jesus has commanded. And one of Jesus’ big teachings was His relationship between Father, Son and Holy Spirit. How His will was connected to the Father. The Spirit’s role in His mission.

In baptism, God puts His Name on you. Whenever I am preparing to baptize a little child, or even an adult, I ask them, “what does it mean when you put your name on something? A bookbag, a desk, a piece of luggage?” Possession. Ownership. Care. Protection. In an adoption, a family places their last name on that child; they become part of the family. A shared name means a new shared identity with the family unit. Parents are pledging to love and protect that child as their own. In baptism God adopts you into His family and puts His Name on you! God’s ownership, possession, care and protection! You’re part of His family now. God’s adopted child! And just as adoption into a family, there are “house rules”—which is the second part of the great commission: 1) baptizing; 2) teaching everything I have commanded.

Baptism is foundational to our identity, so it’s a good place to examine how the theology of the Trinity relates to our everyday life. In the Name of the Father. The Father’s Name is placed on us in baptism. That means we are a child—a son or daughter, in relationship to One who loves us better and more perfectly than any earthly fathers or mothers have loved their own children. And I know how deeply we love our children. But the Father’s love runs still deeper, and He knew every day of our life before one of them ever began. He knew you before the foundation of the world. The Father is our Creator. We’re unique individuals, with the fingerprints of the Father all over our incredible biology and personality and talents and life. Merely living and breathing is a miracle of complexity and organization that witnesses His glory. In generations of study, biologists have only begun to scratch the surface of how amazing the mystery of life is. The study of life has yielded amazing knowledge. How much more will the study of God and His Word also yield up great treasures of wisdom and daily living?

And our personalities are so unique and different, that sometimes we hardly know ourselves. Yet our Father knows every hair on our head, and cares more deeply for us than we even know or realize. He knows us inside and out. The Father is Creator, and we are His creatures. That relation puts us in worshipful awe to the One who commands the stars and the planets, the seas and the mountains, and they all obey. As creatures we acknowledge that He is the One True God and worthy of all worship. And we are thankful for all the blessings of how we are made and all He richly and daily provides us. This is theology—study of the Father.

And of the Son. The Son’s Name is placed on us in baptism. As the Father created, so the Son redeems us. It begins all the way back with the Fall into sin, and God’s rescue plan to save Adam and Eve and their descendants from the sin and death we brought into the world. When God spoke the fateful words of the curse of sin, it was a dark and gloomy day for mankind. An untold future of terrible bloodshed and suffering was to follow. But not all was despair. God launched what one author calls the “Seed Project”—because God promised the Seed or offspring of Eve would come and crush the head of the serpent who had tempted them. God kept that “Seed Project” going through all the history of Israel, through genealogies and promises down through the ages, getting narrower and clearer and closer, until the family ancestry led to Jesus.

Through God’s “Seed Project”, Jesus, the Son of God, entered the world as a human being. Born to live, teach, suffer, die, and rise again for our sins. And when He had risen in victory from the grave He gave this commission to His disciples. How to continue the mission He began. One command with two parts. The one command: make disciples of all nations. The two parts? Baptizing and teaching.

Our identity in Jesus, the Son, is as simple and clear as having been called and adopted into this Christian family, and it is as broad and deep as everything that Jesus has taught. There are lessons enough for a lifetime and more in the Word of God. And baptized into Jesus we are cleansed and washed from all our sins. We are raised up with Him in newness of life, so that we have a new identity to live, move, and walk in Him. As Paul says, “It is no longer I who live, but Christ living in me!” Our sinful flesh no longer rules our life and our desires, but the new man, the new woman of God that we are in Christ Jesus is alive. Christ lives in you to transform your life little by little into His likeness, and away from the image of the world. This and more is the theology, the study of the Son, and how it affects your identity and daily life.

And of the Holy Spirit. The Holy Spirit is the Sanctifier. That’s a strange word to many of us, but it means to “make us holy” or set us apart. Just as the chosen nation of Israel were to be set apart by their obedience to God’s commands in the Old Testament, so also believers, the church, are set apart by the obedience of faith now. Your new life in Christ Jesus is the life of the Spirit living in you. Not the old, former life of sin and deceitful desires; full of selfishness and jealousy and rivalry and ungodly behavior. But the new life purified of sin. The Holy Spirit is our ever-companion, not leaving us abandoned, but constantly pouring into us and out of us the cleansing stream of Living Water, washing our sin away and refreshing us for new life, walking in His ways. Our life in the Spirit is daily rising up anew from the waters of baptism, cleansed and renewed for life toward God, and serving our neighbor.

We briefly describe our Christian identity from Jesus’ great commission: one command—to make disciples, in two parts—by baptizing and teaching. His commission shows God’s intention that we keep all of Jesus’ teaching, and diligently passing it on to the next generation. It shows how the everyday theology of being a student of God and His Word, is part and parcel of being a disciple. That theology is knowing who God is and who you are in Him. It’s knowing what He done, is doing, and will continue to do for you. And it’s knowing how that unfolds for you in the life of the Trinity. Father, Son, and Holy Spirit each take unique roles in shaping your identity and daily Christian life. For all these reasons and more, we have every reason to praise and celebrate the Holy Trinity this Sunday, and every Sunday of the year! In the Name of the Father, and of the Son, and of the Holy Spirit, Amen.