In the church there must be a graduation, a hierarchy, a division of labour, every one doing that for which he is best fitted, just as in the body one member has one office assigned to it, and another another. All Christians, viewed collectively, make up one body, the unity of which is supplied by their relation to Christ. Viewed individually, they stand to each other in the same sort of relation as the different limbs and organs of the natural body, as foot and hand, or hand and eye.
Related Commentaries of Romans 12:4
Romans 12:4-5
4 For as we have many members in one body, and all members have not the same office:
5 So we, being many, are one body in Christ, and every one members one of another.