2.17 There is one body of Christ (this is a first principle of the Faith, according to the NT- although not given the prominence it should be amongst us).
We enter the one body of Christ by baptism into the one body of the Lord Jesus (1 Cor. 12:13). We therefore have a duty to fellowship all who remain in the body (1 Cor. 10:16). Paul describes Peter as not walking according to the truth of the Gospel (Gal. 2:14) by effectively saying there were two bodies, of Jews and Gentiles, and only fellowshipping one of these groups rather than the entire one body. Paul put all the ecclesial politics behind him and withstood Peter " to his face" .If we know " the truth" of Christ's Gospel, we will fellowship all those in Him and in that Truth. If we don't, Paul foresaw that ultimately " the truth of the Gospel" would be lost (Gal. 2:5). Tragically, in man-made attempts to preserve the Gospel's Truth the rest of the body has often been disfellowshipped. But by fellowshipping all the body, the " Truth" is kept!
Eph. 4:25 draws another practical conclusion from the one body of Christ: " Wherefore putting away lying, speak every man truth with his neighbour: for we are members one of another" . If we are one body, there should therefore be truthfulness between us. No white lying, no gross exaggeration, no gossiping, no presentation of facts in a distorted way. Why? Because " we are members one of another" . If we do behave like this, we are really saying that we are not members of the one body. The one body is Jesus; and all that is true of Him must be true of us. He is not divided, and neither should we be, either within our own beings, or as a community. " Be perfectly joined together" (1 Cor. 1:10) uses the same Greek word as in Heb. 10:5, where we read of the Lord's one body " prepared" , joined together. And earlier, in Eph. 4:14,15, the point has been made that because we are not blown around with every wind of doctrine, therefore we deal truly in love (RVmg.). Truthfulness with each other within the one body of Christ is related to our having known and deeply believed the truth of God. The implication is also that by speaking and preaching truth, we " grow up into him in all things, which is the head, even Christ" , who is " the Truth" in every way. Notice how Eph. 4 stresses the need for true doctrine because this is related to truthfulness with each other; if we are not tossed to and fro by false doctrines, then we will speak the truth in love (Eph. 4:14,15); “If so be that ye have heard him, and have been taught by him, as the truth is in Jesus…wherefore [because of this] put away lying, speak every man truth with his neighbour” in the one body of Christ (Eph. 4:21,25).