John 3:4-8 — 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?
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.
That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.
Marvel not that I said unto thee, Ye must be born again.
The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit.
Even if a person was born from a mother's womb a second time, it would still be a birth in sinful flesh, with a fallen nature. Who can bring a clean thing out of an unclean? not one (Job 14:4). This is why Jesus Christ was conceived by the Spirit of God.
Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be. So then they that are in the flesh cannot please God (Romans 8:7-8).
The new nature is born of the Spirit and is spiritual.
water — (NOT baptism — baptism symbolized death, not life) the Word of God. That He might sanctify and cleanse it with the washing of water by the word (Ephesians 5:26).
Being born again, not of corruptible seed, but of incorruptible, by the Word of God, which liveth and abideth for ever (1 Peter 1:23).
You must be born again = "you all" must … All Israel — Then will I sprinkle clean water upon you, and ye shall be clean: from all your filthiness, and from all your idols, will I cleanse you. A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh. And I will put My Spirit within you, and cause you to walk in My statutes, and ye shall keep My judgments, and do them (Ezekiel 36:25-27). A prophecy of the Kingdom.
When the Word is believed, the Holy Spirit accomplishes the new birth and we have a new nature and new life.
You cannot see the Spirit, but you can recognize His power in your life. Verse 8 refers to the believer's life, not the Spirit Himself.
To sum up the teaching in this verse: "The wind bloweth" — there is the fact. "And thou hearest the sound thereof" — there is evidence of the fact. "But knowest now whence" — there is the mystery behind the fact. The one born again knows that he has a new life, and enjoys the evidences of it, but how the Holy Spirit operates upon the soul, subdues the will, creates the new life within us, belongs to the deep things of God. — Exposition of the Gospel of John, Volume 1, by Arthur W. Pink, page 119.