Born Once, Die Twice - John 3:4-7

3:4 Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother's womb, and be born?
3:5 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.
3:6 That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.
3:7 Marvel not that I said unto thee, Ye must be born again.