The Believer baptizes the Believer into Water after one is saved which we call being born again.

Matthew 28:19 - Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost.

Colossians 2:12 - having been buried with him in baptism, in which you were also raised with him through your faith in the working of God, who raised him from the dead.

1 Peter 3:21 - There is also an antitype which now saves us, baptism (not the removal of the filth of the flesh, but the answer of a good conscience toward God), through the resurrection of Jesus Christ,

Acts 10:47 - "Can anyone forbid water, that these should not be baptized who have received the Holy Spirit just as we have?"

This is after salvation, we get baptized in water, by which we confess that we are buried with Christ and raised in Christ to a new life.

Why then should we, the body of Christ be baptized?

According to the Bible, water baptism symbolizes the burial of the old self and the resurrection to new life in Christ. This is portrayed through the act of immersion in water, which represents the death and burial of sin, and the subsequent rising out of the water, signifying new life in Christ. Through obedience, we also, following Jesus' example, who was baptized by John the Baptist. We declare our salvation publicly.

What we do not hear from pulpits at all, is that there is also a very important reason why we get baptized in water. Through baptism we enter into the "royal priesthood". With salvation we became the righteousness of God in Christ, but only after we were baptized we became part of the royal priesthood.

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;

For more insight into the water baptism, and us as believers became part of the "royal priesthood" read the Bible study on "Why was Jesus baptized?"