John 3:7-8 Marvel not that I said unto thee, Ye must be born again. 8 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.
When Nicodemus came to Jesus by night, Jesus gave him an important message. It wasn’t a new message, but one that Isaiah had prophesied of. It wasn’t about salvation in the dispensation of grace. It was about the re-birth of the nation Israel. Israel had been born in the Red Sea when they were baptized unto Moses. But they had long since fallen away by the time Christ came on the scene.
Nicodemus misunderstood what Jesus was saying, thinking he was speaking of a physical birth. But Jesus was talking about the spiritual re-birth of a nation by believing that their Messiah had come. Christ rebuked Nicodemus for being a ruler in Israel and not already knowing these things.
Israel requires a new birth. The body of Christ is a new creature.
Gentiles and heathen were never spiritually born to begin with, so being born again isn’t an option. We have to become a new man, something that was completely foreign to the Jews.
2 Corinthians 5:16-17 ¶ Wherefore henceforth know we no man after the flesh: yea, though we have known Christ after the flesh, yet now henceforth know we him no more. 17 Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.