16 from whom the whole body, joined and knit together by what every joint supplies, according to the effective working by which every part does its share, causes growth of the body for the edifying of itself in love.
The argument of verse 16 is that believers need to cooperate with each other in ministry. Since we belong to each other, we affect one another and have a responsibility to minister to one another.
16 from whom
The “whom” here is Christ (4:15). The church derives its spiritual vitality from Him. There is a relation of “from” in this verse to “with a view to” in verse 15—that is, to grow unto vitality in Christ. The “from” here then indicates that we draw dynamic life from Christ. Jesus is the source for spiritual growth. He is the cause for our growth. We derive all life and power from Him.
the whole body,
The idea of “body” here is not the individual but the church as a whole, in the corporate sense. The members of the body of Christ adapt to one another because they are one body, not many. The church as the “body” receives its instructions from the “head,” who is Christ.
The object of why the body should build itself into an edification construct is found in 1 Corinthians 14:4 “He who speaks in a tongue edifies himself, but he who [expounds Scripture] edifies the church.” The church with an edification construct operates in a mature way. It is not enough that the individual simply edify himself.
“Joined” means to join closely together several parts. Ephesians 2:21 uses this word of a building where different parts of the building make up the whole building. In our verse here the image is one of a body with many different parts to it that are intimately connected. The joints are points of connection between members of the body of Christ. The Greek indicates that it is an ongoing process (present participle) to connect saint with saint.
As the church listens to Bible exposition and saints work together, edification takes place.
A well-ordered church joins together all the dynamics of the body. Members know how to work together. We are one spiritual body. The Holy Spirit joined us together at the point of our salvation when He baptized us into the body of Christ (1 Co 12:13). This is our positional status before God forever. However, the Spirit wants us to experience this truth in our relationships with other believers as well so that there is a connectedness in mutual edification.