“Jesus answered him, ‘Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God.” John 3:3
In the familiar passage above, the words recorded from Jesus are in direct reply to Nicodemas, a Jewish leader (see John 3:10), who approached Jesus by cover of night to make inquiry of Him. Nicodemas began the conversation by affirming that Jesus certainly must be a teacher who comes from God because of the many signs and wonders He has performed, but Jesus neither replies, nor offers related comment. Instead He proceeds directly with the statement made above. What are we to make of this?
The first thing to note here is the statement, “unless one is born again” or literally born from above. Nicodemas seems to have trouble with this statement because he follows up with the expression of his confusion by asking how being born again was even possible, “How can a man be born when he is old? Can he enter a second time into his mother’s womb and be born?” John 3:4 Note here how Nicodemas assumes that being born again has to do with a physical birth, associated with a physical conception, from a physical mother. Why is his distinction important? Because for the Jew, all assumed benefits, blessings, and statuses as the “chosen people of God” were thought to be directly linked to one’s physical, ethnic relationship to Abraham. But Jesus is describing something much different. The very opening verses of John’s Gospel describe this very same distinction, “But to all who did receive [Him], who believed in [His] name, [He] gave the right to become children of God, who were born, not of blood nor of the will of the flesh nor of the will of man, but of God.” John 1:12-13 Notice here, just as in John 3, that a clear distinction is made between one’s physical lineage and the necessity of being born again. John 1 literally says those who believe have been given the right to become children of God. It goes on to contrast this right of progeny with 1. Ethnicity 2. Physical birth 3. Decisionism. An exclamation point is added to this passage with the statement that becoming a child of God is from neither of these options through which man can contribute, but from God alone, leaving one to conclude that the very faith necessary to believe in Christ is likewise from God. The implication of rebirth here is explicitly restated in Jesus’ interaction with Nicodemas just 2 chapters later.
This brings up two related questions. Who then can claim to be children of God and to whom has the right been given? Can physical Jews, because of their ethnic relationship to Abraham claim to be children of God? Can every person simply because of their birth claim God as father? Or better stated, is God a generic father to us all? Or can someone simply choose to join God’s family? Based on these passages, the answer to each of these must explicitly be no. Being a true child of God is not automatically conveyed to a person because of ethnicity or nationality, this includes unbelieving Jews who were convinced that their ethnic claim to Abraham granted them privileged access into the family of God (see John 8 and Romans 2). It also is a corrective to those who claim worldwide inclusiveness to God’s family, though certainly He has a claim to everyone as their Creator. Likewise, this dismisses the notion that anyone, by way of outward steps (raise of hand, walking an isle, praying a prayer or signing a card) can become a child of God.
Jesus takes care to describe this rebirth in John 3:5-8 “Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. Do not marvel that I said to you ‘You must be born again.’ The wind blows where it wishes, and you hear its sound, but you do not know where it comes from or where it goes. So it is with everyone who is born of the Spirit.” There is much that could be said here (for more on this passage see here: Regeneration and Conversion, In Christ, The Wind blows where it wishes), but the focus must be that rebirth, theologically known as regeneration, is the result of the Holy Spirit’s work in the heart and it is necessary to enter/see the kingdom of God. It has been said that repentance and faith in Christ are the first-fruits of regeneration. There is simply no other way, “You must be born again.”
 Or from above