1 Now there was a Pharisee named Nicodemus, a ruler of the Jews.
2 He came to Jesus at night and said to him, "Rabbi, we know that you are a teacher who has come from God, for no one can do these signs that you are doing unless God is with him."
3 Jesus answered and said to him, "Amen, amen, I say to you, no one can see the kingdom of God without being born from above."
4 Nicodemus said to him, "How can a person once grown old be born again? Surely he cannot reenter his mother's womb and be born again, can he?"
5 Jesus answered, "Amen, amen, I say to you, no one can enter the kingdom of God without being born of water and Spirit.
6 What is born of flesh is flesh and what is born of spirit is spirit.
7 Do not be amazed that I told you, 'You must be born from above.'
8 The wind blows where it wills, and you can hear the sound it makes, but you do not know where it comes from or where it goes; so it is with everyone who is born of the Spirit."
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Catholics believe that being born anew, or "born again", occurs through baptism. From the catechism:"
1212 The sacraments of Christian initiation - Baptism, Confirmation, and the Eucharist - lay the foundations of every Christian life. "The sharing in the divine nature given to men through the grace of Christ bears a certain likeness to the origin, development, and nourishing of natural life. The faithful are born anew by Baptism, strengthened by the sacrament of Confirmation, and receive in the Eucharist the food of eternal life. By means of these sacraments of Christian initiation, they thus receive in increasing measure the treasures of the divine life and advance toward the perfection of charity."
Catholics also believe that following this, we continue to go through "conversion" throughout our lives as we spiritually grow. At times this is gradual, and at times it comes forcefully and with great emotion. I've personally experienced it both ways.
From the catechism:"
III. THE CONVERSION OF THE BAPTIZED
1427 Jesus calls to conversion. This call is an essential part of the proclamation of the kingdom: "The time is fulfilled, and the kingdom of God is at hand; repent, and believe in the gospel." In the Church's preaching this call is addressed first to those who do not yet know Christ and his Gospel. Also, Baptism is the principal place for the first and fundamental conversion. It is by faith in the Gospel and by Baptism that one renounces evil and gains salvation, that is, the forgiveness of all sins and the gift of new life.
1428 Christ's call to conversion continues to resound in the lives of Christians. This second conversion is an uninterrupted task for the whole Church who, "clasping sinners to her bosom, [is] at once holy and always in need of purification, [and] follows constantly the path of penance and renewal." This endeavor of conversion is not just a human work. It is the movement of a "contrite heart," drawn and moved by grace to respond to the merciful love of God who loved us first."
