Why must a believer in Jesus be baptized in water

Followers of Jesus are baptized in water as obedience to His command to be baptized, just as Jesus obeyed God’s command to be baptized by John the Baptist.

Followers of Jesus are baptized in water because it is when they are publicly confirmed to be a child of God, just as at Jesus’ baptism God the Father publicly confirmed Jesus to be His Son.

Followers of Jesus are baptized in water because it is when they are commissioned for a life of service to God with the Holy Spirit, just as Jesus was anointed with the Holy Spirit at His baptism so He can be commissioned for a life of service to God.