The Two Prevailing Views: (Chapters twenty-one and twenty-two deal with the literal versus the non-literal interpretation of Scripture)
The Literalist View: They see this passage as a very literal description of New Jerusalem which is Heaven being illustrated—the eternal home for Christians. This is about our inherence and hope, what is to come, about living in the glory of God for eternity. Some see this a wooden, literal description of heaven, and others as a best-as-can-be representation of it. Measure the city is seen as the proof text to this as referring to heaven.
The Non-Literalist View: They see this passage as obviously not literal, but rather symbolic as God dwells among us. They say much of this passage draws from Isaiah 60, and it was not meant to be literal then, thus probably is not meant to be literal for us now, either. How can a person breathe on a high mountain? Or, these dimensions of the city would be too small and/or impractical due to its architectural inconstancies to our understanding of natural laws and physics. This New Jerusalem is not a description of Heaven, but rather the role and purpose of the Church to be the light bearers of Christ. Since the Holy of Holies is the tabernacle of God as He met with humanity, now the Church is what God uses as the means of dispensing His sacraments and modeling His holiness that He calls us to model to others. The Church is God’s representation of His earthly presence as denoted by the statement the names of the twelve apostles (Eph. 2:2-21; Heb. 10:11).
The point in these views? Perhaps both views are what John had in mind and what the Spirit has for us. A description of heaven is something that words can’t convey, but we need this hope and wonder. If we try the best we can, we still may not be able to grasp its reality; however, we can grasp its hope to help us through our daily grind of life. Thus, John lays out heaven so we can see its wonders and perfection. Furthermore, this is also what the Church needs to do in the meantime—represent God on earth. Oh, how we fail so greatly with that!
As an atheist, I, literally, can’t argue with the views you put forth here.