Jesus answered him, I assure you, most solemnly I tell you, that unless a person is born again (anew, from above), he cannot ever see (know, be acquainted with, and experience) the kingdom of God.
Nicodemus said to Him, How can a man be born when he is old? Can he enter his mother's womb again and be born?
Jesus answered, I assure you, most solemnly I tell you, unless a man is born of water and [even] the Spirit, he cannot [ever] enter the kingdom of God. [Ezek. 36:25-27.]
What is born of [from] the flesh is flesh [of the physical is physical]; and what is born of the Spirit is spirit.