How is repentance only until John? Explain.
We spend a lot of time wondering what Jesus meant by being 'born of water', and how that equates to being 'born of the flesh', but Paul speaks plainly of being 'born according to the flesh' in his letter to the Galatians and we see that it means abiding by the law (repentance) without faith. And that is exactly what John preached--repentance according to the righteousness of the law prior to the revelation of faith in Jesus Christ. But as Paul and Jesus both teach, required repentance according to the righteousness of the law is not how a person sees and enters into the kingdom of God. You not only must repent of your unrighteousness, but you must also have faith in Christ to enter the kingdom of God. This is exactly the stumbling block of the Jews. They reject the new birth and rely on the symbolic waters of repentance alone to see the kingdom.
The works of the flesh and produced when a person follows and yields to the lustful desires of the human body.
The flesh is a reference to the human body here in Galatians.
16 I say then: Walk in the Spirit, and you shall not fulfill the lust of the flesh. 17 For the flesh lusts against the Spirit, and the Spirit against the flesh; and these are contrary to one another, so that you do not do the things that you wish. 18 But if you are led by the Spirit, you are not under the law. 19 Now the works of the flesh are evident, which are: adultery, fornication, uncleanness, lewdness, 20 idolatry, sorcery, hatred, contentions, jealousies, outbursts of wrath, selfish ambitions, dissensions, heresies, 21 envy, murders, drunkenness, revelries, and the like; of which I tell you beforehand, just as I also told you in time past, that those who practice such things will not inherit the kingdom of God. Galatians 5:16-21
It is clear that Paul is teaching that the flesh is the human body with the sin nature that indwells and empowers it.
Nicodemus was of the mindset that because he was a descendent of Abraham, that he was entitled to the blessing of Abraham, and that he himself was in Covenant with God by birthright.
Jesus taught him that he must be born again.
He taught him this through the earth concept of natural child birth.
For flesh gives birth to flesh.
JLB