Only God's Spirit gives new life. The Spirit is like the wind that blows wherever it wants to. You can hear the wind, but you don't know where it comes from or where it is going.
Here is the great mystery of our religion: Christ came as a human. The Spirit proved that he pleased God, and he was seen by angels. Christ was preached to the nations. People in this world put their faith in him, and he was taken up to glory.