“See” = “Enter”, the sentences are parallel. “See” = “experience”, e.g., “If you would see good days, keep your lips from evil...” God will not receive anyone into His kingdom unless they are born-again.
The kingdom of God has not fully begun until Christ returns. God's kingdom is partly present in the world now, in a spiritual way. A person can become a citizen of God's kingdom now, through faith in Christ. In that sense God's kingdom shows itself in the world. But the full kingdom is the Lord's visible reign from Jerusalem. The nations will need to pass muster with Christ before any will be allowed in. Matthew 25:31-34, loving conduct toward Christ's family is evidence that the person has justifying faith.
Born from above, or again?Anothen had a double meaning. Both are true. The new birth is not a natural, psychological effect.
Born of water – what does this mean?:
1. Water-baptism? Some have taught that being "born of water" refers to water baptism. Example: “It is true that, by neglecting baptism, we are excluded from salvation; and in this sense I acknowledge that it is necessary” (John Calvin, Commentaries, John 3:5). Calvin's doctrine of salvation and baptism was an effort to harmonize salvation by faith with the traditional Catholic/sacramental view in which he had been raised. British Anglican preacher John Wesley was similarly confusing: “John 3:5 – Except he experience that great inward change by the Spirit, and be baptized (wherever baptism can be had) as the outward sign and means of it” (Wesley's Explanatory Notes on the Bible). However, Christ himself declared the thief on the cross that the thief was surely going to Paradise with him, even though the thief could not be baptized.
Baptism is in light of repentance, not unto repentance -- notice that the preposition “for” in Luke 3:3 means in view of / because of, notin order to get. Peter said the same thing in Acts 2:38: Repent, and be baptized in Christ's name in view of the forgiveness of your sins...”
2. Natural birth? IOW, does "born of water" refer to the breaking water of birth, in other words, one must first be born physically and then spiritually. Not a commonly held interpretation. It seems like pointless information; obviously, one must exist in order to potentially be born again.
3. The Word of God? See Paul in Ephesians 5:26, for a place where it says that the Scripture has a washing effect. Also Jesus in John 15:3. This is a stronger possibility than the first two options, but I can't find an Old Testament example where “water” was a metaphor of the Scripture. Perhaps Christ coined a new metaphor.
4. Water = the Holy Spirit? Sometimes the conjunction kai can be translated as even (“in other words”). "You must be born of water, in other words, born of the Holy Spirit." This would be consistent with other truths Jesus says in this chapter.
5. Repentance of sin? Referring especially to the preaching ministry of John the Baptist, Luke 3:3. "Born of water" then would mean "born of repentance", with the word "water" standing for "repentance" by association.
I like # 3, 4, and 5 the best, and I think #4 has the best Old Testament backing, which would explain why Jesus questioned the acclaimed rabbi Nicodemus for not understanding the idea of new birth (see Ezekiel 36:24-27).