{9} For the body is not one member, but many.

(9) He amplifies that which followed of the similitude, as if he should say, The unity of the body is not prevented by this diversity of members, and furthermore it could not be a body if it did not consist of many members, and those being different.

People's New Testament

12:13-20 For in one Spirit were we all baptized into one body. For by means of one spirit we were all baptized into one body (Meyer). Rather, moved by one spirit acting through the apostles and evangelists, we were all baptized into one body, whether Jews or Gentiles, bond or free. The idea is that though diverse in race and condition, all have been made parts of one body by baptism, and that this had all been done under the direction of one spirit. All, too, receiving it as a gift, drank of the same spirit. Hence, if special and extraordinary spiritual gifts were imparted to the members of this body, these would be due to one spirit.

Jamieson-Fausset-Brown Bible Commentary

14. Translate, "For the body also." The analogy of the body, not consisting exclusively of one, but of many members, illustrates the mutual dependence of the various members in the one body, the Church. The well-known fable of the belly and the other members, spoken by Menenius Agrippa, to the seceding commons [Livy, 2.32], was probably before Paul's mind, stored as it was with classical literature.

Matthew Henry's Concise Commentary

12:12-26 Christ and his church form one body, as Head and members. Christians become members of this body by baptism. The outward rite is of Divine institution; it is a sign of the new birth, and is called therefore the washing of regeneration, Tit 3:5. But it is by the Spirit, only by the renewing of the Holy Ghost, that we are made members of Christ's body. And by communion with Christ at the Lord's supper, we are strengthened, not by drinking the wine, but by drinking into one Spirit. Each member has its form, place, and use. The meanest makes a part of the body. There must be a distinction of members in the body. So Christ's members have different powers and different places. We should do the duties of our own place, and not murmur, or quarrel with others. All the members of the body are useful and necessary to each other. Nor is there a member of the body of Christ, but may and ought to be useful to fellow-members. As in the natural body of man, the members should be closely united by the strongest bonds of love; the good of the whole should be the object of all. All Christians are dependent one upon another; each is to expect and receive help from the rest. Let us then have more of the spirit of union in our religion.