Jesus teach us about the new spiritual childhood in the gospel of Luke: "People were also bringing babies to Jesus for him to place his hands on them. When the disciples saw this, they rebuked them. But Jesus called the children to him and said, "Let the little children come to me, and do not hinder them, for the kingdom of God belongs to such as these. Whosoever does not receive the Kingdom of God like a child shall not enter in", Luke 18:17. But this birth, this new spiritual infancy, is the passage from error (heresies) to truth (wisdom), achieving truth and charity are gifts, qualities of God.
In this spiritual childhood we share the nature of God and receive eternal life, which is the concretion of hope: "This is eternal life, that they know you the only true God", John 17:3. The new childhood is the fruition of the spiritual gifts we inherit from God, the fruition of faith and justification. In baptism we receive hope, the spirit, but this spirit must bear fruit through the path of piety (firmness, constancy, devotion, equanimity, stability) and mercy (compassion, amability, affability, benedicence, benevolence) and on this path there are obstacles, heresies that are presented to us as deceptive teachings (The law of the Talion, "eye for eye and tooth for tooth" in Matthew 5:38, "Love your neighbor and hate your enemy", in Matthew 5:43)
The disciples know this new birth in Pentecost (Acts of the apostle 2), this new birth is the result of a progressive mind (ethical thinking). The spiritual gifts are progressive: "Be renewed in the spirit of your minds", Ephesians 4:3.
We are born again when we receive the holy spirit (Gnosis): "When the apostles in Jerusalem heard that Samaria had accepted the word of God, they sent Peter and John to Samaria. When they arrived, they prayed for the new believers there that they might received the Holy Spirit, because the Holy Spirit had not yet come on any of them; they had simply been baptized in the name of the Lord Jesus. Then Peter and John placed their hands on them, and they received the Holy Spirit." Acts 8:14-17
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