John is the one Isaiah the prophet was talking about when he said, "There is someone shouting in the desert: 'Prepare the way for the Lord. Make the road straight for him.'"
Many Pharisees and Sadducees came to the place where John was baptizing people. When John saw them, he said, "You are all snakes! Who warned you to run away from the punishment that God is about to send?
I know what you are thinking. You want to say, 'but Abraham is our father!' That means nothing. I tell you, God could make children for Abraham from these rocks.
"I baptize you with water to show that you have changed your hearts and lives. But there is someone coming later who is able to do more than I can. I am not good enough to be the slave who takes off his sandals. He will baptize you with the Holy Spirit and with fire.
He will come ready to clean the grain. He will separate the good grain from the straw, and he will put the good part into his barn. Then he will burn the useless part with a fire that cannot be stopped."