kom'-un: koinos, in the classics, and primarily in the New Testament, means what is public, general, universal, as contrasted with idios, what is peculiar, individual, not shared with others. Thus, "common faith" (Tit 1:4), "common salvation" (Jude 1:3), refer to that in which the experience of all Christians unites and is identical: "common," because there is but one faith and one salvation (Eph 4:4-6). From this comes the derived meaning of what is ordinary and, therefore, to be disesteemed, as contrasted with what pertains to a class, and to be prized, because rare. This naturally coincides with Old Testament exclusivism, particularity and separation. Its religion was that of a separated people, with a separated class as its ministers, and with minute directions as to distinctions of meat, drink, times, places, rites, vessels, etc. Whatever was common or ordinary, it avoided. The New Testament, on the other hand, with its universalism of scope, and its spirituality of sphere, rose above all such externals. The salvation which it brought was directed to the redemption of Nature, as well as of man, sanctifying the creature, and pervading all parts of man's being and all relations of life. The antithesis is forcibly illustrated in Ac 10:14 f, where Peter says: "I have never eaten anything that is common and unclean," and the reply is: "What God hath cleansed, make not thou common."
H. E. Jacobs