Text: Isaiah 6:1-7
“Blessèd be the Holy Trinity and the undivided Unity. Let us give glory to him because he has shown his mercy to us.” This Sunday is one of the few, if not the only, Sundays, where we focus not on an event in our Lord’s ministry or life, but a doctrine. In Scripture, the God of all creation reveals Himself to us as a Trinity: Father, Son, and Holy Spirit. All three are co-eternal and co-equal, none existing apart from or without another. We worship one God in three Persons. This is how God has revealed Himself to us.
Unfortunately, over time different and competing understandings of God began to spread. The Jews, for example, believed in the Trinity in the Old Testament, but rejected it when the Son of God became flesh. The Gnostics also rejected the divinity of Jesus. Both of these are addressed in Scripture, in St. Paul’s letters and St. John’s. But, then, in the fourth century, a pastor named Arius began teaching that there was a time when the Son of God didn’t exist. He was a very popular pastor, and his teaching in part led to the Nicene Creed being written, and also the Athanasian Creed.
Today, the Church sets aside time to both praise our eternal, Triune God and to firm up and make clear our confession of faith in the Trinity. We asked in the Collect of the Day that God would keep us steadfast in this faith and preserve us against all adversity. In Sacred Scripture, the one true God reveals Himself to us as a Trinity, who alone takes away our guilt and pardons our iniquity.
I said that today we want to firm up and make clear our confession of faith in the Triune God. The first step in that, though, is acknowledging that we aren’t going to understand everything. There will never be a time in this sinful flesh, when we will perfectly understand the Trinity. I am confident that we will in the new creation; But, for now, we see as in a mirror dimly, St. Paul said. St. Paul also said in our Epistle text, “Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are His judgments and how inscrutable His ways!” This passage comes at the end of St. Paul’s discussion of another difficult doctrine, predestination. I’ve always pictured him, at this point, as just throwing up his hands, confessing his faith in the Trinity, and being done for the day. And, that’s actually how it ends. He says, “For from Him and through Him and to Him are all things. To him be glory forever. Amen.”
That text is good, because St. Paul’s brings out this idea: that we aren’t called to understand everything, but believe. Consider the doctrine of the Trinity. We aren’t called to understand every little bit and piece of it, but we are called to believe it and confess it as truth. Why? Because the Triune God is the true God, who takes away the guilt of our sins and pardons our iniquity. That is plain what the Scripture says. We like to tell ourselves we live an age of science and reason, and we must therefore have a logical backing, first, before we can believe anything. You aren’t going to prove the Trinity from human reasoning nor from science. Don’t even try. Instead, believe; because that’s what Scripture says. It is written, “I will destroy the wisdom of the wise, and the discernment of the discerning I will thwart.” Our Lord also said, “I thank you, Father, Lord of heaven and earth, that You have hidden these things from the wise and understanding and revealed them to little children.” The Triune God has hidden Himself from human reason, but reveals Himself even to little children through Scripture.
Okay, so we aren’t going to understand the Trinity this side of Eden. That’s alright. We aren’t called to totally understand what has been revealed to us, but to believe it. St. Peter says it this way,
Our beloved brother Paul also wrote to you according to the wisdom given him…there are some things…that are hard to understand, which the ignorant and unstable twist…as they do the other Scriptures. You therefore…take care that you are not carried away…but grow in the grace and knowledge of our Lord and Savior.
We aren’t called to understand, but believe. And, in order for us to believe in the Trinity, it must first be revealed to us. In Scripture. Where, in Scripture, is the Trinity – one God in three persons – revealed to us?
We’ll start with the words straight from our Lord’s mouth. “Go therefore and make disciples of all nations, baptizing them in the name (notice, singular) of the Father and of the Son and of the Holy Spirit.” We remember also the revelation of the Trinity at Jesus’ Baptism. Remember how the Father spoke from heaven, the Spirit descended as a dove, the Son in the water? Just last week, in the Gospel lesson, Jesus said this: “The Helper, the Holy Spirit, whom the Father will send in My name…will teach you all things.” Jesus even proved the Trinity, along with His own being God, from the Old Testament. One time the Pharisees came to Him, and Jesus asked them, “How is it then that David, in the Spirit, calls [the Christ] Lord, saying ‘The Lord said to my Lord, sit at my right hand, until I put your enemies under your feet.’” Jesus linked the Holy Spirit, the Father, and the Son together from the Old Testament and pointed out that David believed in the Trinity.
Time doesn’t permit us to list all the other proofs of the Trinity in the New Testament, how Sts. Paul, John, and Peter, James, and Jude all make mention, as do the Gospels and the letter to the Hebrews. But, what about the Old Testament? Is the Trinity just a New Testament thing? Nope. Where can we go to prove the Trinity from the Old Testament, and show that Old Testament believers knew this doctrine?
The simplest place to go, and the one you already know, is Creation. “In the beginning, God created the heavens and the earth.” Later it says, “God said, ‘Let us make man in our image, after our likeness.’” Then it says, “God created man in His own image.” Even in English, you can hear the one God saying, “Let us.” In Hebrew, the word for God here is Elohim, which is plural. And yet, all the actions are singular. And, of course, it also says in Genesis 1, “The Spirit of God was hovering over the face of the waters.”
The easiest place to go to prove the Trinity from the Old Testament is Genesis 1. But, how can we prove Old Testament Christians believed this, and that we aren’t just making it up after the fact? Fast forward to Moses. In his final days, he spoke to the people of Israel, “Is not [God] your Father, who created you?” Moses mentioned the Father specifically. Move forward to King David. In Psalm 33, he linked all three persons together when he said, in addition to the Father, “By the Word of the Lord (Jesus) the heavens were made, and by the breath of His mouth (the Holy Spirit) all their host.” You could go backwards to Job, which some believe is the oldest book, and hear, “By His Spirit the heavens were made.” You could jump to Isaiah, two hundred years after David, or to Ezra – some three hundred years after that – both of whom speak of the Father, the Spirit, and the promised Messiah. Suffice it to say, not only is the Triune God revealed to us also in the Old Testament, but the Old Testament Church believed in and confessed its faith in the Trinity.
So now, why talk about all this? Why take a Sunday and cram this all in? Or, why even talk about the Trinity? After all, a large chunk of the world believes in “God,” whatever that means. Couldn’t we just, for the sake of unity, jettison the talk of the Trinity and hope that it’ll all sort out in the end? That doesn’t really jive with the Creed we just confessed, which all Christian church bodies believe, “Whoever desires to be saved, must above all, hold the catholic faith. Whoever does not keep it whole and undefiled will without doubt perish eternally. And that catholic faith is this, that we worship one God in Trinity and Trinity in unity.”
Why talk about the Trinity? Because this is how the true God has revealed Himself to us. He alone, is the true God who has acted in and throughout history. And, not only has He acted, but He’s acted for us. See, when Isaiah saw God in our text, he feared for his very life. The seraphim were crying out, “Holy, holy, holy is the Lord of hosts,” and Isaiah knew God’s holiness and our unholiness cannot coexist. Then, one of the angels flew to him and touched his lips with a hot coal from the altar of sacrifice. He said, “Behold, this has touched your lips; your guilt is taken away, and your sins atoned for.”
We talk about the Trinity because it’s how God has revealed Himself, and it’s how He has revealed Himself for us. God the Father created us, He takes care of us and provides for us. He guards and defends against all evil. For us men and for our salvation, the Son of God took on flesh. He shed His blood for us so that we might live. When His blood touches our lips in the Sacrament, our guilt is taken away and our sins atoned for. God the Holy Spirit, reveals this truth to us through the Scripture. He calls us to faith, and preserves us in the same until we die. We confess our faith in the triune God, not fully understanding, but believing that He is true and has taken away our sin. “Blessèd be the Holy Trinity and the undivided Unity. Let us give glory to him because he has shown his mercy to us.”
 Rom. 11:33.
 Rom. 11:36.
 1 Cor. 1:19.
 Matt. 11:25.
 2 Pet. 3:15-18.
 Matt. 28:19.
 Jn. 14:26.
 Matt. 22:43-44.
 Duet. 32:6.
 Ps. 33:6.
 Job. 26:13.
 Is. 6:7.