Indeed, it is his message that is of utmost importance to the hearer and the reader, a message intended to prepare the way for the one coming after him. The coming of the kingdom necessitates a reorientation of life for those who would be ready to enter that kingdom. Apparently the urgency of John's message was recognized by many people, as reported in v.5. Although the Pharisees and the Sadducees had their distinct differences, Matthew here lumps them together to represent, even at this early stage of the gospel, the unbending opposition that both John and Jesus would encounter from the authorities. John pulls no punches when he assails these leaders, comparing them to snakes fleeing for their lives before the onrush of the consuming fire.
True repentance is a matter of actions as well as words.
Verse 10 continues the eschatological theme of Judgment. John's baptism of water is symbolic of the repentance he proclaims in the wilderness. John's water baptism is not able to bring the power needed for life in the kingdom, nor does his baptism affect the Judgment of the Messiah. Water baptism prepares those who are repentant for the coming Judgment involved in the decision for or against Jesus. When our attention is focused in Advent only on the celebration of the birth of the baby Jesus, John's message of repentance is a timely reminder of the eschatological nature of our faith.