In these verses, in the Gospel of Matthew, Jesus enters the Temple for the last time. Even while he teaches, the chief priests and elders of the people challenge his authority. The context in Matthew for this challenge seems to include Jesus’ cleansing of the Temple, his miraculous healing, and also, perhaps, his teaching in the Temple. In his response to this challenge, Jesus mentions John the Baptist and his entire ministry, including his baptism. In doing so, Jesus is not being evasive. He is trying to get the chief priests and elders to recognize that John was, indeed, sent by God, so that they will then be able to recognize Jesus as the Messiah, about whom John prophesied. If they gave the correct answer to the question that Jesus asked, they would know from where Jesus’ authority comes.
The answer of the chief priests and elders that they did not know is loaded with meaning. This is evident in the way they argued among themselves how they must respond. Thus, what they were in effect saying was that they knew, but did not want to say it aloud because that would lead to their being trapped in their own net. If they answered that John was from God, they would have to also answer why they did not accept him and his baptism. However, even more than that, they would have to answer why they are not accepting Jesus to whom John pointed. They could answer that John was not from God, or of human origin, since they were afraid of the people who regarded John as a prophet from God. This leads them to realize that it better not to answer at all. Jesus responds by refusing to answer their question, since they have shown that they do not have the authority to ask it. Since they have not opted for John, they have not opted for Jesus.
While it is true that a person will not know the answer to all questions and “I do not know” is an accepted and legitimate response because of the fragmentary nature of human knowledge, we must be careful in using “I do not know” when we really mean that we do not want to know or do not want to say. We may not want to know because the knowledge that we profess to have will demand a response from us. We may not be ready for this response and, thus, hide our closed minds under the words “I do not know”. We may not want to say because we are afraid of the consequences that our views will have, on us and, on others. We may prefer to let things be as they are rather than rock the boat and topple over ourselves.