When God had something important to say in the Old Testament, he usually told the prophets first. The prophets were God’s messengers. They had a really cool job—they got to speak for God! They also had a really hard job—most people didn’t want to listen to God.

Isaiah was one of the most famous prophets in Israel’s history. He saw some things no one had ever seen before. Like the time he saw the Lord sitting way up in the air on a throne. (Now, we really can’t see God—he’s invisible, after all—but sometimes people in the Bible got to see things that showed what God is like.) Isaiah saw a big robe filling up the temple. He saw angels covering their eyes because God was too wonderful to look at.

And even more amazing than what he saw was what Isaiah heard. If you want to get people’s attention while speaking to them, you might raise your voice. If you want to get their attention while writing to them, you might make everything bold or underlined. But if you didn’t have a computer and you didn’t want to scream, you would repeat yourself. That’s how they did things in the Bible. When something is extra special in the Bible, it often gets repeated.

Only one thing about God in the Bible is said not just once or twice, but three times in a row. It’s what Isaiah heard from the angels: “Holy, holy, holy is the Lord of hosts; the whole earth is full of his glory!” That means God is the best, the biggest, and the brightest in the whole world. It means he’s better than you can imagine. It means when we really get to know God, we’ll know how much we are not God.

Which is why Isaiah said, “Woe is me! I have seen the King! I am a man of unclean lips, and I dwell in the midst of a people of unclean lips.” One glimpse of God was all it took to convince Isaiah of two things: he was a sinner, and he needed a Savior. After Isaiah saw what no one had seen before, he saw in himself what all of us need to see over and over: we’re not holy in ourselves, but God is.

Thankfully, God is also gracious. He sent an angel to touch Isaiah’s lips and make him clean. “Your guilt is taken away,” the angel said, “and your sin has been covered.” The God who is holy can make us holy too.