(Do not) yield... your (body) members as instruments of unrighteousness... 

     Until the late 1860's there was a general nonconformity in U.S. railroad track gages ranging from 4'-8-1/2" to 7'-0" wide. Several rail lines used interchangeable vehicles called "compromise cars" which had extra wide flanges on their wheels to compensate for the different track widths. Although "compromise cars" were widely used, they were the cause of many accidents. One of the worst happened on December 18, 1867 at Angola, New York when a "compromise car" derailed and fell from a bridge into a ravine causing death and injury to its passengers.
     Just as the "compromise cars" caused many a train's derailment, compromising with sin will also cause the derailment of one's fellowship with Christ. Therefore, be diligent that you "let not sin... reign in your... body..." (Rm 6:12). For "blessed is the man that walketh not in the... way of sinners" (Ps 1:1).