Luke 3.7: He said therefore to the crowds that came out to be baptized by him, “You brood of vipers! Who warned you to flee from the wrath to come?” (ESV)
John the Baptist was a prophet and as such he spoke with prophetic authority. Like the prophets in the Old Testament he could perceive by divine inspiration the very character and nature of people’s lives. And in this case many, maybe all, of the people coming out to see him were of a very bad character. And John spoke very bluntly to them calling them children of snakes. We can conclude that the people individually and collectively were living in a way that was contrary to God’s plan. But God was drawing them out to see John for redemptive purposes.
The people were coming out and receiving a baptism of repentance. No one was forcing them into this. They desired it and therefore they were turning to God. This was the first step of renewal. The people were symbolically expressing through this baptism of John that they were turning away from their sin and pointing themselves in the direction of living life the way God wanted them to. John’s baptism did not have the full revelation of Jesus the Messiah built into it. But John’s preaching of repentance worked as the foundation for the people to be ready to believe in the one who was coming after him. To believe in Jesus who was about to be revealed.
In Acts 19.1-7 there is recorded an event in the Apostle Paul’s travels where he met some disciples of John the Baptist in the city of Ephesus. During Paul’s conversation with them he says in verse 4: “John baptized with the baptism of repentance, telling the people to believe in the one who was to come after him, that is, Jesus.” And repentance is essential for us likewise. Jesus said in Luke 24.47 about himself after he was raised from the dead, “that repentance and forgiveness of sins should be proclaimed in his name to all nations, beginning in Jerusalem.” (ESV)