The passage
      v19. Initially the Gentiles felt, and most likely were treated, as if they were second-class citizens in the Christian church. It was only natural for Jewish believers to relate to the Gentile converts in much the same way as they related to the God-fearing Gentiles who attended their synagogues. This view Paul sought to break down, for he understood that they were "no longer foreigners and aliens, but fellow citizens with God's people (Jews) and members of God's household."
      v20. Paul now describes a building where the apostles and prophets are the foundation and Christ is the cornerstone. The building is the eternal assembly, the heavenly city of God, the heavenly temple, where believers are even now gathering with Christ. The local assembly of believers, the church, is actually a visible image of this eternal building, a building where Gentiles are an integral part.
      v21. As the cornerstone, Jesus defines and ties the whole building together and becomes the architectural defining point from which the building takes shape. So, the heavenly assembly, as with the church, evolves out of Jesus into a complete entity - a complete whole.
      v22. This building, this house, this community of believers, initially consisted of the remnant of Israel - the apostles and Jewish believers. This group is now extended to include "you too", ie. Gentile believers. Believing Gentiles are similarly included in this new building, are similarly incorporated into this "holy temple", this "dwelling in which God lives by his Spirit". God has always "tabernacled" with his people, and now "through" the Spirit of Christ, he dwells with the gathered believers in the heavenly assembly, as here in the local gathered congregation. All believers, Gentile and Jew, share this privilege.

Defining the church
      In our passage, Paul the apostle gives us three ways of looking at the church. Although we can look at church from the aspect of history, sociology, buildings and organization, in the end, church is a congregation of believers.

1. Community
      The church is a society of "fellow citizens", members of a "household", a community where the barriers of race and religion are no more. So, the first way of seeing the church is as a society of friends.
      Sadly, there are a number of factors which work against church as community, for example:
        i] Size. Group dynamics tells us that a group larger than 12 has difficulty maintaining meaningful contacts. Most churches are larger than that so we will always tend toward the impersonal.
        ii] The "otherness" of worship. Liturgy, in particular, tends to personalize worship; it is between the individual and God, rather than each other and God. It is easy to be part of a liturgical worship service without being part of each other.
        iii] Selfishness. Sin, of course, does its thing, moving our eyes onto self such that we see little of the needs of others.
      Once we begin to see church as community we can begin to look beyond ourselves to those who sit about us. Individual prayer points can become precious to us. The barriers will start to come down when we see ourselves as a society of friends.

2. Eternity
      Believers, members of an often fragile and faulty human organization called the church, are actually part of an eternal organization, a building which incorporates Christ and the apostles and all believers from all ages and all places. This building, this heavenly assembly, is even now gathered and our little congregation actually images it. So, a second way of seeing the church is as a shimmering reflection of an eternal reality.
      There are lots of distractions in church life that draw our eyes from the light to the shadows. Issues over the color of the church carpet, finances, committee appointments and the like, even worries over size (did Jesus really mean "two or three"?). Yet, with a little concentration on the words of a hymn, light playing through a stain-glass window, a sermon, the oft repeated words of a liturgical prayer, and all of a sudden we can see again that we are part of an eternal society.

3. Spirituality
      The local church is the earthly dwelling-place of our living God. The assembled people is the "holy temple" of God, the place where he dwells. So, a third way of seeing the church is as a community indwelt by the Spirit of Christ - a spiritual society.
      The business of recognizing Jesus in our midst is not an easy one. When we come together we often forget in whose presence we have gathered. The tendency today is to meet for fellowship, or to meet for outreach (accessing unbelievers), but there can be only one reason and that to meet with Jesus. Once we see Jesus present in our meetings, it is then we become a truly spiritual society.

v20
      epoikodomhqenteV (epoikodomew) aor. pas. part. "built" - having been built [upon]. Possibly a divine passive.
      tw/ qemiliw/ (oV) "foundation - that on which a structure is built*.
      twn apostolwn kai profhtwn "of the apostles and prophets. These two genitive nouns are probably appositional in that they further define the noun "foundation"; "the foundation that consists of ....." It is possible that the genitives are a genitive of source, "the foundation laid by the apostles and prophets", NEB. For example, the foundation of the gospel laid by the apostles. None-the-less, we are safer with, "the foundation consisting of the apostles and prophets", O'Brien.
      profhtwn (hV ou) "prophets" - The missing article has prompted the suggestion that Paul intends "apostles who prophecy", Grudem.
      akrogwniaiou (oV) "cornerstone" - the cornerstone or capstone of a building, essential to its construction*. The "chief cornerstone" of the building is "Jesus himself". When it was finally clear that God's purposes for humanity could no longer be worked out through the nation of Israel, the prophets began to speak of the creation of a new building, a new Israel. This new community would evolve out of the faithful remnant of the old through the intervention of God's messiah, his anointed one. The messiah was described in different ways. One description used in the Old Testament was that of a "stone" - a building stone within a new building. It was a "precious" stone, but a "stone of stumbling". Sometimes it was described as a "foundation" stone - the new building would be built on it. It was a "cornerstone" - defining and holding the building together. It was also described as a "cap-stone" (key or top stone) - the final top stone which held the top arch of the building together. Here in Ephesians the stone is probably the cornerstone - Christ defines and ties the building together.