What does Matthew 3:3 mean?
Matthew has introduced John the Baptist as a man preaching a simple message in the wilderness: Repent, for the kingdom of heaven is at hand (Matthew 3:1–2). Now Matthew directly connects John to the prophecy in Isaiah 40:3, "A voice cries: 'In the wilderness prepare the way of the Lord; make straight in the desert a highway for our God.'"To Isaiah's original audience, this text was about preparing the literal roadway for the Israelite exiles to return to Judah from captivity in Babylon. Matthew, like the writers of the other Gospels, shows this verse is also about John the Baptist preparing the way of Jesus and those who would follow Him. John's role was to symbolically "clear the path" for Jesus by calling Israel to repent of sin and turn back to the way of God. If they did so, they would be ready to follow God's Son. As it was with the proportion of those who returned to Judah from Babylon, only a small percentage of Israelites would turn and follow Christ.
Matthew also continues to make the connection between the experiences of the nation of Israel and the life of Jesus.