What do you mean “Born Again”?

We continue studying the Gospel of John thinking about Jesus first encounter with the Pharisee Nicodemus.
We look at the familiar, yet perhaps confusing, phrase “Born Again” and ask the question, what, precisely, did Jesus mean by that? If Jesus tells us that no-one can see the Kingdom of God without being born again, then it is essential we get our understanding of this right.
We think about the citizenship that we aquire by natural birth, and pose the question, does that mean our spiritual rebirth grants us a different kind of citizenship, and begin to unpack what Jesus was pointing people towards.