The key word/phrase in chapter 4? Perhaps it is “building up.” “And he gave the apostles, the prophets, the evangelists, the shepherds and teachers, to equip the saints for the work of ministry, for building up the body of Christ” (4:11-12). “The whole body, joined and held together by every joint with which it is equipped, when each part is working properly, makes the body grow so that it builds itself up in love” (4:16). “Let no corrupting talk come out of your mouths, but only such as is good for building up” (4:29).
In the church, God has given leaders and he has given gifts, all for the purpose of building up his people so that “we are to grow up in every way into him who is the head, into Christ” (4:15). This growing and maturing takes place only in the context of the congregation where God has given all that is necessary for us to grow and to become like Christ. Thus, the importance, no, the necessity of a real and robust relationship to and membership in the local body of believers as we all grow up into Christ.
The church’s one foundation
is Jesus Christ, our Lord;
we are a new creation
by water and the Word.
From heav’n he came and taught us
what perfect love can be;
through life and death he sought us,
and rose to set us free. -- S. J. Stone (1866)