Why was Jesus baptized?

When John at first did not want to baptize Jesus, Jesus said "Permit it to be so now, for thus it is fitting for us to fulfil all righteousness."

Matthew 3:13-15 - Then Jesus came from Galilee to John at the Jordan to be baptized by him and John tried to prevent Him, saying, "I need to be baptized by You, and are You coming to me?" But Jesus answered and said to him, "Permit it to be so now, for thus it is fitting for us to fulfil all righteousness." Then he allowed Him.

What does this mean when Jesus said "to fulfil all righteousness"?

When Jesus was baptized "all righteousness" was fulfil. Jesus was already righteous and so it could not be for Him to become righteous.

There must have been something else that had to be done.

Jesus knew that He would become our High Priest and we would become a royal priesthood. He also knew that He was from the tribe of Judah and therefore He could not be in the priesthood.

Hebrews 7:14 - For it is evident that our Lord arose from Judah, of which tribe Moses spoke nothing concerning priesthood.

Hebrews 7:24 - But He, because He continues forever, has an unchangeable priesthood.

John was the son of Zacharias and Elizabeth, both from Levi and therefore John was also in line to become a priest after his father, but he did not as he was the one who had to prepare the way for Jesus. Which way did he prepare? It was the way into the priesthood.

Deuteronomy 18:1a - "The priests, the Levites, all the tribe of Levi . . .

We the body of Christ, some from the gentiles and some of the Israelites, from all tribes, could never become part of the royal priesthood if it was not for Jesus that was baptized. But not only baptized, but baptized by John.

1 Peter 2:9 - But you are a chosen generation, a royal priesthood, a holy nation, His own special people, that you may proclaim the praises of Him who called you out of darkness into His marvellous light.