There was a man of the Pharisees, named Nicodemus, a ruler of the Jews:
The same came to Jesus by night, and said unto him, Rabbi, we know that thou art a teacher come from God: for no man can do these miracles that thou doest, except God be with him.
Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God.

COMMENTARY

There was a man of the Pharisees, named Nicodemus, a ruler of the Jews
Let us consider the example of Nicodemus. The man was a ruler in the Jewish faith, which faith had been God’s covenant gospel for more than a millennium before the coming of Jesus.
Nicodemus also seems to have been a sincere seeker of truth. Though many of his peers were only going through the motions, he was able to recognize and pursue the Son of God on earth. He therefore seems to have been about as ideal a follower of God as one could ever hope to find.

Except a man be born again, he cannot see the kingdom of God
Even to this sincere follower, Jesus indicated that there was a reformation that he needed to embrace. Good as Nicodemus was, he still required a rebirth before he would be able to see the kingdom of God. Of course that rebirth is a reference to baptism, but baptism itself suggests an internal rebirth of the soul, a fundamental change of beliefs and perspectives.
Jesus’s prescription of rebirth is not limited to Nicodemus either. By his own words, he applied it to us all. The fact that Nicodemus was born a Jew and I was born a Christian makes no difference. For though my name has always been listed on a church record, that is not the same thing as having actually awoken to the reality of Christ. Not a one of us have that awakening by default, it is something that we must pursue with earnest.
Between birth and rebirth, we will undoubtedly develop a few misconceptions along the way. When at last we gain enlightenment, we will finally be able to start correcting them.