In Judaic tradition, baptism was a ritual immersion for spiritual purity. This ritual, called Tevilah was performed to purify yourself before going into God's presence. It was usually performed in a Mikveh which is a Jewish ritual bath so one could emerge purified to go on to worship and offer sacrifices to God.

John was not baptizing as a ritual immersion, neither was he doing it at a Mikveh. Instead, John was on a mission to call Israel to repentance, God called John to prepare the way for the coming Messiah. He was to baptize those who accepted his message, hence this was a purification through repentance and acceptance of John's message. His message was centered around Jesus, the coming kingdom with its demands of citizenship and a warning of the ultimate judgment. John made clear that he was merely a vessel of God by denying that he was neither Christ, Elijah or a prophet but stated,

"I am a voice of one crying in the wilderness, 'Make straight the way of the Lord,' as Isaiah the prophet said." - John 1:23

Those who were baptized acknowledged their sins and declared their faith, believing that through the Messiah's coming, they would be forgiven of their sins. Even though Jesus had no sins to confess as he was already pure, He had unapparent reasons for doing it. First off, as most of the things Jesus does, he did it as an example for us to follow, that we should make our commitment to him a public declaration to everyone. Secondly, Jesus did it to fulfill the prophecy of Isaiah that John had mentioned. John was calling people to follow after the Messiah, so when the dove came down from heaven and God declared that Jesus was His son, the people followed after Him. This leads into the next point as Jesus went into ministry proceeding His baptism; He used the baptism as a way to dedicate himself to His own work, affirming His mission on earth. Through His baptism, Jesus was also identified as a symbol of the Passover sacrifice and gave a foreshadowing of His sacrificial death on the cross.

Nowadays, we practice baptism as our formal declaration of our commitment to follow after Jesus in laying down our sins and picking up our cross to follow after Him. When we are submerged under the water we symbolize Jesus' sacrifice and resembling our death to sin. Upon ascension from the water, we declare that we are made a new creature in Jesus and that we are a part of His family. For Christian communities, this is a proud moment but can seem mundane for some. However, for people who come from other religions such as Islam, Hinduism, Buddhism and the like, who have converted to Christianity, this is a very big deal. It is seen as an act of shame for them to become a Christian and can result in punishment of unemployment, being disowned and possibly even death.