When a Gentile converted to Judaism part of the conversion process involved a ritual washing in the mikvah, a ritual washing pool.
So when Jesus tells Nicodemus that to see God's kingdom one needed to be "born of above" or "born anew" and Nicodemus, a well trained man of Torah, acts confused, Jesus asks, "How do you not get this?" And Jesus specifies, "You must be born of water and Spirit".
This new birth means, of course, more than simply the ritual washing in the mikvah. Christians have long and always interpreted John 3:5 as a clear reference to Baptism. Christian Baptism, of course, has its antecedent in the Jewish mikvah, in particular we see St. John the Baptist doing something unique with ritual washing--calling people to repentance in anticipation and expectation of Messiah's arrival, of the coming King who brings with Him God's kingdom. And thus John offers a washing of repentance, fulfilling the role of the Elijah in Malachi's ancient prophecy of Elijah calling Israel to repentance before the Day of Yahweh.
At the conclusion of Matthew's Gospel Jesus gives the Apostles the Great Commission, telling them, "Make disciples of all nations, baptizing them in the Name of the Father, Son, and Holy Spirit, instructing them of all that I have taught you."
On the Day of Pentecost, in Acts 2, the Spirit poured out upon the disciples in fulfillment of John the Baptist's words, "I baptize you with water, but He will baptize you with the Holy Spirit and with fire" St. Peter says these words to the gathered Jewish pilgrims in Jerusalem, "Repent and be baptized, all of you, in the name of Jesus Christ for the forgiveness of sins, and you will receive the gift of the Holy Spirit, this is for you and for your children, and for all who are far off, as many as the Lord our God will call."
St. Paul in Romans 6 writes, "Don't you know that all of us who have been baptized into Christ were baptized into His death? We were buried with Him in Baptism unto death, so that even as Christ was raised from the dead by the glory of God the Father we too might walk in newness of life." And also in Galatians 3, "All of you who were baptized into Christ have put on Christ."
St. Peter in his epistle perhaps makes the point more clear, "This represents Baptism which now saves you, not as a cleaning of dirt from the body, but as a pledge of new conscience before God in accordance with Christ's resurrection"
"You must be born again" "You must be born of water and Spirit"
In the name of the Father, Son, and Holy Spirit.
Into Christ.
For the forgiveness of sins.
Receive the Holy Spirit.
Cleansed by water with the Word.
It now saves you.
A clean conscience before God.
Buried with Christ.
Crucified with Christ.
Raised with Christ to new life.
"Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come." - 2 Corinthians 5:17
-CryptoLutheran