To encourage people with the truth that Jesus identifies with us fully. We see this at Jesus' baptism, when He identified with sinners by being baptised even though He was sinless.
To teach that John the Baptist said to the people in Palestine that their actions needed to match what they claimed to believe, and his words are still relevant today!
To teach that some messages we receive need acting upon immediately, like the message that John the Baptist gave to the Jewish people living in Palestine.
