So we, being many - We who are Christians, and who are numerous as individuals.
Are one body - Are united together, constituting one society, or one people, mutually dependent, and having the same great interests at heart, though to be promoted by us according to our special talents and opportunities. As the welfare of the same body is to be promoted in one manner by the feet, in another by the eye, etc.; so the welfare of the body of Christ is to be promoted by discharging our duties in our appropriate sphere, as God has appointed us.
In Christ - One body, joined to Christ, or connected with him as the head; Ephesians 1:22-23, "And gave him to be head over all things to the church, which is his body;" compare John 15:1-7. This does not mean that there is any physical or literal union, or any destruction of personal identity, or any thing particularly mysterious or unintelligible. Christians acknowledge him as their head. that is, their Lawgiver; their Counsellor, Guide, and Redeemer. They are bound to him by especially tender ties of affection, gratitude, and friendship; they are united in him, that is, in acknowledging him as their common Lord and Saviour. Any other unions than this is impossible; and the sacred writers never intended that expressions like these should be explained literally. The union of Christians to Christ is the most tender and interesting of any in this world, but no more mysterious than what binds friend to friend, children to parents, or husbands to their wives; compare Ephesians 5:23-33. (See the supplementary note at Romans 8:17.)
And every one members one of another - Compare 1-Corinthians 12:25-26. That is, we are so united as to be mutually dependent; each one is of service to the other; and the existence and function of the one is necessary to the usefulness of the other. Thus, the members of the body may be said to be members one of another; as the feet could not, for example, perform their functions or be of use if it were not for the eye; the ear, the hand, the teeth, etc., would be useless if it were not for the other members, which go to make up the entire person. Thus, in the church, every individual is not only necessary in his place as an individual, but is needful to the proper symmetry and action of the whole. And we may learn here:
(1) That no member of the church of Christ should esteem himself to be of no importance. In his own place he may be of as much consequence as the man of learning, wealth, and talent may be in his.
(2) God designed that there should be differences of endowments of nature and of grace in the church; just as it was needful that there should be differences in the members of the human body.
(3) no one should despise or lightly esteem another. All are necessary. We can no more spare the foot or the hand than we can the eye; though the latter may be much more curious and striking as a proof of divine skill. We do not despise the hand or the foot any more than we do the eye; and in all we should acknowledge the goodness and wisdom of God. See these thoughts carried out in 1-Corinthians 12:21-25.

So we, being many - We who are members of the Church of Christ, which is considered the body of which he is the head, have various offices assigned to us, according to the measure of grace, faith and religious knowledge which we possess; and although each has a different office, and qualifications suitable to that office, yet all belong to the same body; and each has as much need of the help of another as that other has of his; therefore, let there be neither pride on the one hand, nor envy on the other. The same metaphor, in nearly the same words, is used in Synopsis Sohar, page 13. "As man is divided into various members and joints, united among themselves, and raised by gradations above each other, and collectively compose one body; so all created things are members orderly disposed, and altogether constitute one body. In like manner the law, distributed into various articulations, constitutes but one body." See Schoettgen.

So we being many are one body in Christ,.... This is the application of the above simile. The chosen of God, the redeemed of Christ, and those that are justified by his righteousness, and sanctified by his Spirit; though they are but few in comparison of the men of the world, but considered in themselves are many, and yet make up but one body, the church, of which Christ is the head: and though this general assembly; or church universal, may be distinguished into several congregational churches, and distinct communities, yet each community, consisting of divers persons, is but one body "in Christ", united and knit together by joints and bands, under him their head, Lord, and King; in him, and not in Caesar, or any earthly monarch, to distinguish this body from bodies politic, or any civil community among men:
and everyone members one of another; as in union with Christ their head, so to one another in love, walking in holy fellowship together, sympathizing with, and serving each other.

So we - All believers. Are one body - Closely connected together in Christ, and consequently ought to be helpful to each other.