One idea to which Saint Paul frequently returns is the comparison between the faithful who are in Christ Jesus and the members of a human body. He makes use of this metaphor several times to prove several different things to prove, for example, in one place that each has a separate work to do, and in another place that each separate work is dependent on the rest. But while in this fashion making use of a comparison which has occurred to many writers before his time and since, Saint Paul gives it an elevation and a nobleness that raises it above the dignity of a mere literary device. For him it is evidently a real truth which is to be of help to a soul in its outlook upon life. We must remember, first of all, the circumstances in which Saint Paul found himself. He was a convert from Judaism, where he had been brought up in the very strictest form of the Hebrew faith; he was "a Pharisee of the Pharisees," that is, he belonged to the narrowest, most fanatical, and most exclusively nationalistic of the various parties of his nation. Then had come his sudden and miraculous seizure on the road to Damascus, and all the old fierceness was turned now into a burning and impetuous love of Christ. His education, while certainly designed with care under Gamaliel to lead him to a whole-hearted acceptance of the Law, evidently brought him into touch with Greek and Roman culture. He quotes passages from the poets, and in his address to the Athenians shows considerable sympathy with the nobler side of paganism. Moreover, his missionary tours among the Hebrew communities in the Greek cities of Asia Minor made him realize that not these communities alone, but all the world was longing ("groaning") for a new and more perfect revelation. His missionary venture thus became more and more an appeal, not to the circumcised (for these had their own valiant apostles) but to the gentiles.
Saint Paul took, that is to say, for his own portion, the most degraded religion with which he came in contact. Now what is his method of dealing with these poor souls? He at once endeavours to make them realize their own value in the sight of God. He tells them that they are all members of Christ. These people who have been accustomed to worshipping idols, and who have looked upon gods as heroes of very doubtful morality, who have never been assisted to rise above their own surroundings or to improve their stunted spiritual life, are now confronted by the ideals of Christianity, which certainly must have appeared to them more dazzling and even more impossible than they do to us, who are familiar with the character of Christ. And while in this way they suddenly found life become very much more difficult, and were contrasting their old natural or unnatural practices with the new purity and continence demanded of them, Saint Paul, instead of telling them that they are sinners and upbraiding them with their failures, is at great pains to point out to them how God by becoming man has raised man to God. He reveals the whole story of the Incarnation in its culminating mercy of the Crucifixion. They have been bought at a great price: if man has not valued them, God has. But not merely has Christ died for them, He has made them one with Himself. The sacraments knit them to Him; the Eucharist is a memorial of that death, transfigured to an abiding presence. Matrimony is but a type of the union between Christ and each single soul; and the ensuing love is so fierce and vehement that it breaks down every barrier, sweeps aside every obstacle, and makes each one with Christ: "I live now, not I, but Christ liveth in me."
Here is comfort, not for them only, but for me as well. I am a member of Christ; I have been purchased by the Blood of God. Then I am of value in His sight; He thinks me worth troubling about. But not only has He redeemed me, but He has given me the grace to be a member of His Church, a member of His mystical body. I have, then, a certain definite place in this organization, and do a work that others, indeed, might have done, yet which He has confided to me alone. Not only have I thus my own vocation; because I am the member of a body, I have a definite function to perform, but one which needs the co-operation of others. I and they are interdependent. We require each other, and every single Catholic has demands on me, on my good works, prayers, etc. But even more than I am dependent on my fellow-members, I am dependent even on Christ and He on me. To me, miserable, poor, foolish, sinful, it is also given to "fill up what is wanting in the sufferings of Christ"; for if "one member suffers, all the members suffer." He is my Head. Yet surely this ought to inspire me to go on with my struggle in life. This should give me courage to persevere. Just as I find that I can only hope to reform others - children, sinners, the poor - by making them realize the good they can do and the goodness that is really in them, so is it also with myself. I shall surely do better when I realize my own dignity as a Christian soul. I, even I, am a member of Christ. Then I shall take care not to sully my reputation or lower myself. I shall have an esprit de corps, a loyalty to my chief, that will keep me conscious that in my hands is the honour, not of myself only, but of all my fellows on earth and in heaven, and of God Himself. For "if one member suffers, all the body suffers also."
- text taken from Meditations for Layfolk by Father Bede Jarrett, O.P.