What did Jesus' baptism in the Jordan accomplish?
It symbolically fulfilled the washing required for the priesthood, since He had no sin to repent of, and it identified Him with His covenant people, the nation of Israel. The water itself did not cleanse; it pictured the spiritual cleansing needed for priestly service.
Les explains that Jesus had no sin to repent of and no personal need for baptism. Rather, He came to fulfill all the requirements of the priesthood symbolically. Going down into the Jordan, He symbolically fulfilled the washing of the priesthood. At the same time, He identified Himself with His covenant people, the nation of Israel. As Les notes, everything holds together and there is a reason for it, but we have to understand it.