Summary: The focus here is the union with Christ that produces the communion with one another as his body.
In the previous passage Paul has taught that everyone in the church has spiritual gifts, that they all come from the same source, viz, God, and that they are to be used for the common good. With these gifts in mind, he now impresses upon them the profound truth of their union in Christ. They are not a mere collection of individual believers who associate together for a common cause. They are not merely a spiritual family of related believers. They make up the one body of Christ.
In our passage next week, Paul will develop the theme of the body having many and varied members, all of whom have important functions. The focus here is the union with Christ that produces the communion with one another as his body.
For just as the body is one and has many members, and all the members of the body, though many, are one body, so it is with Christ.
Note the remarkable phrase, so it is with Christ. Paul gives us the metaphor of a body. Just as a body has arms and legs and eyes and ears that are necessary for it to be fully functional, so the members of the church body serve necessary functions. But Paul doesn’t use the word “church”; he says so it is with Christ.
What a profound equation! The church is equated with Christ. How so? In verse 27 he says, Now you are the body of Christ and individually members of it. We, each of us who have been saved by our Lord, somehow make up his body.
The next verse gives us some idea how this works. 13 For in one Spirit we were all baptized into one body—Jews or Greeks, slaves or free—and all were made to drink of one Spirit.
Do you remember what John the Baptist said about Jesus? I baptize you with water for repentance, but he who is coming after me is mightier than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit (Matthew 3:11). This verse confirms John’s prophecy. All of us become Christians by virtue of Jesus baptizing us with the Holy Spirit.
That baptism changes us. The word used here for baptism is baptizo; it is the same word used for pickling, say, a cucumber. What happens when a cucumber is “baptized” in vinegar? It becomes a pickle. Its nature changes. The baptism of the Spirit changes our identity so that instead of being regarding as isolated individuals or as belonging to some other distinct group of people, our identity is found in being members of Christ’s body.
So, whether we are Jew or Greek (i.e. everyone not a Jew) or slave or free (the basic worldly distinction) – whatever the case – once we are baptized with the Holy Spirit we are, in God’s sight, seen as members of Christ’s body.
The last analogy reinforces this unity – and all were made to drink of one Spirit. This is reminiscent of a promise made by Jesus: “If anyone thirsts, let him come to me and drink. Whoever believes in me, as the Scripture has said, ‘Out of his heart will flow rivers of living water.’ ” Now this he said about the Spirit, whom those who believed in him were to receive (John 7:37-39).