John lived a life without worldly influence. His diet of locusts and honey displayed his reliance on God. His dress was similar to that of the prophet Elijah (2Kings 1:8). John preached that God’s judgment was imminent, and urged repentance for the Jews, fulfilling the prophecies of Isaiah 40:3 and Malachi 3:1. Baptism is an outward symbol of this repentance. At the time, only new gentile converts to Judaism, called proselytes, were baptized, but John called the Jews themselves to repentance and baptism. The Jews at the time believed that as God’s chosen people, and descendants of Abraham, they had no need for baptism.
The Pharisees and Sadducees did not approach John’s ministry with sincerity. John brazenly confronted their idea of being justified by Abraham. John called them brood of vipers, the offspring of serpents. The serpent was a deceiver, as in the Garden of Eden. In response to their claim of being children of Abraham, Jesus called them children of the father of lies (John 8:44). Satan is the father of lies, the serpent. Jesus is the only way to God, anything else is false.
John told them to bear fruit, or display earnestly to God the transformation of repentance. This is consistent with being “born again”, which Christ spoke to Nicodemus about(John 3). Jesus spoke of fruit bearing trees as John did. The time for repentance was and is immediate, as the “axe” is always “laid to the root of the trees”. John preached that the Messiah was coming, and God’s judgment would be executed by him.
John foretold that Jesus was greater than himself. John’s urging of repentance and prophecy of the coming judgment prepared the way for Jesus, the true redeemer. Whereas John baptized with water, Christ would baptize with the Holy Spirit, giving the Spirit of God to guide and convict the believer, and to seal the believer as his own. He will baptize with fire, a purifying fire, a refining fire for the soul, and set hearts on fire for God.
What is meant by winnowing fork and chaff? John used the action of threshing wheat to illustrate the judgment of God. The wheat was tread on to loosen the kernels of grain from the chaff, which was the inedible casing around it. A winnowing fork is used to toss the the mix into the air, so the wind would blow the lighter chaff away. The chaff was gathered and burned. The wheat was stored for use. The chaff is the unrepentant, and could expect God’s judgment. The wheat is the repentant believer, saved by Christ.