Water as symbolic cleansing in religious ritual has a long history, back to the earliest times of Ancient Egypt. In Israel's history it became incorporated into synagogue practice, especially when their Pharisee sect began recruiting converts from other nations.

At the time of Jesus most synagogues had a 'mikveh' (מִקְוָה), a ritual bath for cleansing in which the person descended into the water, in contrast to ritual sprinkling. For a non-Jew, Jewish identity commenced after teaching and male circumcision, when a convert would stand in this water while the commandments were read before being received out of the ritual bath as 'a child of one day', that is - new-born into the faith of Israel.

This practice and Nicodemus' acquaintance with it, is assumed in Christ's corrective statement in John 3:5 and 3:10 –

"Jesus answered, 'Truly, truly, I say to you, unless one is born of water and the Spirit,
he cannot enter the kingdom of God...'."; and,
Jesus answered him, "Are you the teacher of Israel and yet you do not understand these things?".

Both John the Baptist and Jesus baptised converts, Jesus surpassing John in the number being baptised in a discipleship baptism under His ministry (Jn.4:1).

Christian baptism builds from this base, but takes its significance from special proxy events in the life of Jesus Christ Himself.

"Do you not know that all of us who have been baptized into Christ Jesus were baptized into His death? We were buried therefore with Him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life. For if we have been united with Him in a death like His, we shall certainly be united with Him in a resurrection like His." (Rom.6:3-5).

The act of baptism is a personal confession of faith in Jesus Christ concerning His substitutionary death and resurrection on behalf of all who come to Him. It cannot therefore be an involuntary act imposed by the belief of another even if that other be a parent or head of state.

As such, its significance defines individual Christian identity and therefore the character of the Christian Church.

It requires no specially endowed person to baptize the believer. This is clear in Paul's approach to those baptized in Corinth during his establishment of the church in that town.

"I thank God that I baptized none of you except Crispus and Gaius, so that no one may say that you were baptized in my name.
(I did baptize also the household of Stephanas. Beyond that, I do not know whether I baptized anyone else.)." (1Cor.1:14-16).

Baptism is thus clearly a passive act, administered to the believer by a baptised believer, in confession of his or her faith in Christ.

As symbolic of the death of the old life, immersion in water is an essence of the act, as the word itself, 'baptizo' (βαπτίζω), signifies.

Although various streams of Christianity have produced modified baptismal practice which tradition has tended to make the norm, the original practice is still represented in the Lateran Baptistery in Rome (built in 440 AD) where the immersion bath is the centre of the dedicated building, in an octagonal shape to celebrate Christ's resurrection on the eighth day of the week in which He died for us.