John 3:8 is, indeed, an evocative but challenging image. "The wind blows where it wills, and you hear the sound of it, but you do not know whence it comes or whither it goes; so it is with everyone who is born of the Spirit" (RSV).
It helps to realize that the Greek text uses the same word for spirit and wind, so there is something of a play on words that doesn’t translate into English.
Jesus is speaking here to Nicodemus, who is confused about what Jesus means when he talks about being "born again." Jesus explains that it isn’t a literal rebirth, but a return to Source. "That which is born of the flesh is flesh and that which is born of the Spirit is spirit" (John 3:6). In other words, the "rebirth" is a surrender of human demands and limitations and a return to the Oneness with Spirit that is our true source and identity. This surrender can’t be defined or justified to our mortal mind, any more than people at that time could define the wind, except by feeling its effects as it passed. When we are "born of the Spirit," we express as the wind expresses, in the loving guidance and flow of Holy Spirit.
This may seem to mortal mind like a loss of power and identity; in Truth, however, it represents a new dimension of freedom and empowerment.