One reason you can’t just think of Jesus as a great teacher is that Jesus claimed to be more than that. You’ll remember at Caesarea Philippi, Jesus asked the disciples, “Who do you think that I am?” (Matt. 16:13). And Peter answers on behalf of all of them, “You are the Christ–you are the Messiah–the Son of the living God” (Matt. 16:16). And Jesus says to Peter, “You’re right. God has revealed this to you” (Matt. 16:17).
And you can even see the tremendous truth claims about Jesus in the shape of the Gospels. Jesus is an amazing teacher. And so the Gospels had things like Matthew 5–7 that contain the Sermon on the Mount. But think of it. One third of the Synoptic Gospels (Matthew, Mark, and Luke) and up to maybe a half of the Gospel of John are focused on the last week of Jesus’ life. Why? Because Jesus didn’t just come to teach. He came to die and to be raised again from the dead because he is the Lamb of God, who comes to take away the sins of the world (John 1:29).