While we are waiting, we read this passage from Matthew.
John the Baptist preached repentance. In looking forward, they also were looking back. John and his appearance and his words recalled for them the prophet of an earlier time, Isaiah, who had also preached repentance and hope.
John was addressing people who were living geographically in the land promised to them, but the conquering Roman army was occupying that land. John preaches to them that the kingdom of heaven has come near. Many are listening and responding. They come from the city of Jerusalem and from all over the country to hear John and to be baptized by him.
To summarize, so far: John preached. People responded.
Matthew tells us that among the crowds that came to hear John and be baptized by him, some religious leaders also showed up. John addressed them sharply, calling them names. Look back at Isaiah 28 to read judgment on the corrupt rulers, priests, and prophets of his time--and, to John's time, and, to ours.
Charles Cousar, Texts for Preaching, A Lectionary Commentary Based on the NRSV-Year A:
What John attacks is the presumptuousness of the Pharisees and Sadducees. The prophet had written, "look to the rock from which you were hewn...Look to Abraham your father" (Isa 51:1-2). The problem was that the rock had become something behind which to hide, a place of supposed protection, a spot of security. John challenges the privileged position claimed by the Pharisees and Saducees...Repentance has to do not only with remorse over past failures, but also with a new heart and a changed life...Today, as we loyal church-goers argue about who gets to get married in our churches or even is welcomed there, we need to be careful not to rely on our own sense of being holier than any of those folks who may disagree with us about unimportant or important topics. After all, don't all of us on both side of debates believe that our side is closer to what Jesus wants than those other misguided people who can't see how right we are and have always been?