John the Baptist said, “I baptize you with water for repentance, but he who is coming after me … will baptize you with the Holy Spirit and fire. His winnowing fork is in his hand, and he will clear his threshing floor and gather his wheat into the barn, but the chaff he will burn with unquenchable fire.” (Matthew 3:11-12)
Jesus will baptize with the Holy Spirit and fire. He will winnow wheat to the barn and chaff to the fire. The baptism with fire in this verse is not a blessing but judgement. Israel must be winnowed, believers and unbelievers must be separated not in preparation for the coming of the Lord (i.e. Jesus) but by the Lord. John is the one calling out in the desert to make ready the way of the Lord (2:3) but he is not the one who makes rough places plain. That is the Lord’s role. This is why John protested when Jesus came to be baptized. John, along with the rest of the nation, needed to be winnowed by Jesus but Jesus needed no winnowing. When Jesus was baptized it wasn’t for repentance or judgement, but so that God’s favor on Jesus might be shown. (2:17)
After Jesus’ temptation in chapter 4, his righteousness is established and the rest of his ministry is winnowing. The nation is divided between true Israel to whom the Gentiles will be joined and “Israel who is not Israel” or hardened Israel who will be judged.