Saint Augustine's 'City of God'

Augustine was a “church father” that lived between 354-430 A.D. He is credited with influencing some of the most notable theologians in history including Martin Luther & John Calvin. But how many of us have read anything in detail by Augustine? Might I suggest a revisit to the classics of Christian literature with a FREE copy of “City of God” (LINK) by Augustine.
In the book, Augustine contrasts two “cities” – one earthly & one heavenly, or “of God”. He contrasts the world's way of thinking against that of the New Testament Church, describing the latter as "the heavenly city, the Heavenly Jerusalem." It is no coincidence that the Bible says the “country”, the “city” that Abraham was really seeking was a “heavenly one”, (Hebrews 11:16). Our forefather Abraham was looking forward to the enduring glories of the New Testament eternity in which we now abide.
City of God -- Book XIV Chap. 28
Of The Nature Of The Two Cities, The Earthly And The Heavenly.
Accordingly, two cities have been formed by two loves: the earthly by the love of self, even to the contempt of God; the heavenly by the love of God, even to the contempt of self. The former, in a word, glories in itself, the latter in the Lord. For the one seeks glory from men; but the greatest glory of the other is God, the witness of conscience. The one lifts up its head in its own glory; the other says to its God, "Thou art my glory, and the lifter up of mine head." In the one, the princes and the nations it subdues are ruled by the love of ruling; in the other, the princes and the subjects serve one another in love, the latter obeying, while the former take thought for all. The one delights in its own strength, represented in the persons of its rulers; the other says to its God, "I will love Thee, O Lord, my strength." And therefore the wise men of the one city, living according to man, have sought for profit to their own bodies or souls, or both, and those who have known God "glorified Him not as God, neither were thankful, but became vain in their imaginations, and their foolish heart was darkened; professing themselves to be wise,"--that is, glorying in their own wisdom, and being possessed by pride,--"they became fools, and changed the glory of the incorruptible God into an image made like to corruptible man, and to birds, and four-footed beasts, and creeping things." For they were either leaders or followers of the people in adoring images, "and worshipped and served the creature more than the Creator, who is blessed for ever." But in the other city there is no human wisdom, but only godliness, which offers due worship to the true God, and looks for its reward in the society of the saints, of holy angels as well as holy men, "that God may be all in all."
Couple what Augustine said with what Scripture says about New Jerusalem & we begin to see how it is that Christians can be physically living in the “earthly” city yet really are citizens of the “heavenly” city.
Revelation 21:1-3 – New Jerusalem
Then I saw a new heaven and a new earth, for the first heaven and the first earth had passed away, and there was no longer any sea. I saw the HolyCity, the new Jerusalem, coming down out of heaven from God, prepared as a bride beautifully dressed for her husband. And I heard a loud voice from the throne saying, "Now the dwelling of God is with men, and he will live with them. They will be his people, and God himself will be with them and be their God.
We can see how at regeneration the “new man” enters the “new Eden”, the “new Promised Land”, and the “new Jerusalem”, wherein they dwell with God. But what about this other city? What about Augustine's “earthly” city? According to many prophecy teachers that city is supposed to be utterly destroyed. They read Rev 21:1-3 & see the old earth passed away, thus they conclude it must be physically destroyed before the new heaven & earth can come. But how do they account for this next passage?
Revelation 22:14-15 – The Earthly City does not continue as a "city," its population reduced to homeless, stray "dogs" outside
Blessed are those who wash their robes, that they may have the right to the tree of life and may go through the gates into the city. Outside are the dogs, those who practice magic arts, the sexually immoral, the murderers, the idolaters and everyone who loves and practices falsehood.
Now note, this is AFTER New Jerusalem comes down. Even more important there are only 5 more verses & then the last word, in the last book of the Bible is completed yet we see no eradication of those outside the gates of the “heavenly” city. Thus, to be “in the city” is to be in Christ. To be outside the city is to be outside Christ. The earthly world, with all of its varieties of religions & cultures are NOT inside the “City of God” unless they are IN CHRIST (& everyone is NOT automatically in Christ, despite what some people advocate, it is NOT a “new world” UNTIL the old man is made new by “rebirth”).
The society of saints transcends any physical borders. The nation of the Elect’s only passport is repentance, which is required for admittance. Enter these gates, enter this city & find true rest from your “journey”. Rest in Christ, our eternal Sabbath.
The “culture” of this society is NOT the culture of the world, not the culture of the former city, but the culture of the “heavenly” city is the culture of Christ. It is not changed by modern or postmodern movements or any other movements of men. But the city of God has its own culture, easily known to all who dwell there. Kingdom dwellers love to glorify God & are humble to even debase themselves instead, so that God & Christ are the only light shinning. Those within the city are not offended that they receive not glory in themselves – this is not the “Chronicles of Narcissia” where everything is about man & what man wants & can do. – rather this is the City of GOD.  Its ALL about HIM -- He is ALL IN ALL.
Revelation 21:22-23 – Christ is the culture of Christians
I did not see a temple in the city, because the Lord God Almighty and the Lamb are its temple. The city does not need the sun or the moon to shine on it, for the glory of God gives it light, and the Lamb is its lamp.
There is no reason to rebuild an earthly temple for God would never dwell there, for He now resides in the new city where there is not a temple, for God Almighty & the Lamb are its temple. The culture of Christians ought be foremost the glory of Christ & not the vain glorying of men & their desires & pretentious “accomplishments”. Art, writing, speaking, music making & all other facets of “culture” among Christians ought to be done in the “light” of Christ as the lamp of the new city in which Christians are supposed to dwell. Amen & Amen

I would add to this the question: so where are we now, you and me regular Christians still in this biological, mortal, natural body?  Since we are not yet changed into a form like God, we conclude that we do not yet see His face, (1 John 3:2 & Rev 22:4), therefore we have yet to fully enter the New Jerusalem City. So, where are we in this Rev 21-22 picture?  We, who are still in the body of flesh, are still at the gates "washing our robes" to gain admission, Rev 22:14, (or "keeping Christ's commandments," as some manuscripts read).  Entrance to the New Jerusalem is granted via Resurrection, for angels guarding the ever open gates, Rev 21:12,  make sure no impure thing ever enters the City, Rev 21:27, for "flesh and blood cannot enter the Kingdom of God," 1 Cor 15:50.  The determination to admit to the City or reject is the Judgment that follows one's death, Heb 9:27, LINK.