Today, we celebrate Trinity Sunday—the day we set aside a little time to think our way through what exactly it means that God is Three in One and One in Three. Being that this is one of the deepest mysteries of the Christian faith, we’re not going to get all the answers today. But what we are going to do is change gears a little bit and spend some time in the Old Testament—Isaiah, specifically, where we’ll think about both who God is and how Isaiah encounters God.

Scripture: Isaiah 6:1-8
In the year that King Uzziah died, I saw the Lord sitting on a throne, high and lofty; and the hem of his robe filled the temple. Seraphs were in attendance above him; each had six wings: with two they covered their faces, and with two they covered their feet, and with two they flew. And one called to another and said:
‘Holy, holy, holy is the Lord of hosts;
the whole earth is full of his glory.’
The pivots on the thresholds shook at the voices of those who called, and the house filled with smoke. And I said: ‘Woe is me! I am lost, for I am a man of unclean lips, and I live among a people of unclean lips; yet my eyes have seen the King, the Lord of hosts!’

Then one of the seraphs flew to me, holding a live coal that had been taken from the altar with a pair of tongs. The seraph touched my mouth with it and said: ‘Now that this has touched your lips, your guilt has departed and your sin is blotted out.’ Then I heard the voice of the Lord saying, ‘Whom shall I send, and who will go for us?’ And I said, ‘Here am I; send me!’

So let’s set the scene. By the time Isaiah arrives on the scene, the kingdom of Israel had been divided into two separate nations: Israel in the north, which contained 10 tribes, and Judah in the south, which contained Jerusalem and the tribes of Judah and Benjamin. Israel was overrun by Assyria in 732 BCE, and its people were scattered into exile or lived as conquered people. Around the time of our text, Judah, which is where Isaiah lived and prophesied, was also under siege by neighboring empires. But in the ancient world, political realities always had a theological overlay—the idea being that if the people were not paying attention, not holding up their end of the covenant that God had made with them, not following God’s laws and walking in God’s ways, then God could and would choose to withhold protection and abundance from them. To be conquered was to be seen as a people whose god had turned away from. This is not something that we’ve carried over into Christianity, but it was very much what the people of ancient Israel believed.

We find Isaiah, then, in the Temple in Jerusalem. This was, for the people of God in that time, the place where heaven and earth met—the holy of holies, at the center of the Temple, was the gateway to God’s throne room. The High Priest could only enter once a year, after much personal and corporate purification, and even then they would tie a rope around his waist so that if he was struck down, they could pull him out.

There is no mention anywhere that Isaiah, however, is the High Priest. You’d think that would be a relevant detail. And yet somehow, Isaiah is caught up to the throne room—brought into the very presence of God and the Divine Council seemingly without warning—and there, he encounters the infinite holiness of God.

What Isaiah describes sounds both impossible and slightly ridiculous to our modern ears: seraphs with six wings, the foundations of the house shaking at their song, the smoke from the incense.

And yet, it feels familiar. Even as we just celebrated Pentecost and all of the ways God is with us and within us—there is still a great deal of mystery in our faith. There are still a million ways in which the mind of God is unsearchable and millions more moments when the enormity of God’s power seems unbearable and unknowable.

The question might creep into the back of our minds: why would a God who sits on a throne in the presence of the Divine Council, with seraphs to sing praise and honor and glory unceasingly, care what I’m up to? Why would this holy God want to come and dwell within me, to care for my Sunday tears and my Monday frustrations and my Friday exhaustion?

But that is the promise, isn’t it? That God does care for us, and God does see and care about what we do—that God calls us to live in a particular way as a particular people, and God is willing to love us into that way of life.

Isaiah acknowledges that he is a man of unclean lips, who dwells among people of unclean lips—he knows himself, and he knows what’s going on in the kingdom of Judah. He knows about the king’s lies and the ill-advised alliances. He knows the ways the political and economic systems have failed to care for the vulnerable, the immigrant, the stranger, the widow and the orphan. He is fully aware that his sinfulness is on display in front of God’s holiness, and he panics.

But God does not strike him down. Instead, he’s given a sort of baptism by fire—both literally and metaphorically—and all of that is burned away. His awareness and his confession were met not with the fires of wrath, but with the fire of mercy.

And immediately, the voice of God becomes clear to him: “Whom shall I send? Who will go for us?”

Hold up. Go where? Send who to do what?

It’s unclear whether Isaiah knew what he was signing up for, though he’d probably figured it out by now: this was the moment he would become a prophet.

Now, we tend to think of prophets as fortune-tellers, people who see into the future and make predictions. But that’s not what a prophet was, or is. A prophet was mostly a messenger—someone who would speak to God’s people on God’s behalf, and intercede for the people with God. But rather than being a sort of divine email service, these people had access to the very heart of God. They took on God’s righteous anger, God’s compassion, God’s lament, and God’s hopefulness in and through their own lives.

The whole book of Isaiah is an outpouring of all this—from Isaiah 2, where God envisions people from every nation under heaven coming together to learn peace, to the rest of this chapter, which is a preview of what’s coming if Judah doesn’t turn around and stop what they’re doing, to Isaiah 40, which was written after the exile as God sent a message to comfort the exiles and call them back to Jerusalem.

The call of a prophet is where God’s holiness and God’s compassion meet.

Because, you see, God’s unsearchable holiness—the pure goodness and light and power and joy that is the presence of God—is also the source of God’s passion, and God’s love and care for us. In the ancient times, which Isaiah bears witness to, this meant calling the people to repentance in no uncertain terms. It sounds harsh to us, but this was God’s pleading with the people to be the sort of society that they were designed to be—one that models the care, the goodness, the joy of God for the whole world. In the New Testament, we see Jesus doing the same work in a new way: offering forgiveness and healing, teaching a divine love and a human equality that goes beyond all reason, and modeling peace and patience for all who knew him.

And that work has continued through the centuries in all sorts of people: Nelson Mandela and Dr. Martin King, Jr; Dorothy Day and Rachel Held Evans; St. Augustine and St. Francis; Julian of Norwich and Rachel Denhollander. Musicians, writers, activists, clergy and laypeople, world-famous and completely unknown.

These prophets, in the way of Isaiah, call us to be holy because we are beloved. They call us to do better because God’s love is deeper and God’s mercy is wider, because God’s ways are higher than our ways. To bear the heart of God for the sake of the people: that is the work of a prophet.

Now, I’m still astounded that Isaiah would volunteer for a job like this. Because prophets are, during their lifetimes, almost always controversial and despised. The people who stand up to say “this is wrong” in the face of enormous power generally aren’t welcomed with open arms.

Not all of us are called to be full-time prophets. But each of us has a little bit of the prophetic in us, I think. You know that little twinge in your gut when you see or hear something that you know is out of line? That’s the heart of God in you. The hours you put in defending the vulnerable, caring for the sick, comforting the grieving, advocating for the radical love of Jesus? That’s the heart of God in you. That pointer finger that comes up when you raise a question about a policy or a decision that you know will do more harm than good? That’s the heart of God in you.

To be holy is to be set apart—to be different. To step out, even with faith in this God who is holy and mighty and loving, can be scary. I don’t think a day or a week goes by where I’m not terrified of something that God asks me to do.

And yet, I can say “here am I, send me,” not because I am confident in my own abilities. Goodness no. I can say that because I learned first to sing along with the seraphs: “holy, holy, holy is the Lord of hosts—heaven and earth are full of God’s glory.”

As one of my own favorite prophets used to tell me nearly every day, the earth is full of the steadfast love of God. And when faced with evidence to the contrary, I am willing to say “not today, Satan.” I am willing to trust in God’s unsearchable holiness, to say ‘yes’ to the prophetic love and infinite hopefulness of that God for as long as I can sing, because I believe that the God of the universe is also the God of our Mondays.

So, beloved people of God, let us sing Isaiah’s song together, knowing that the Triune God—Father, Son, and Holy Spirit—is with us, to the very end of the age.