The apostle teaches that while we should manifest Christian courtesy we are authorized to deal in plain terms with sin and sinners; that this is not inconsistent with true charity. "Whosoever committeth sin," he writes, "transgresseth also the law: for sin is the transgression of the law. And ye know that He was manifested to take away our sins; and in Him is no sin. Whosoever abideth in Him sinneth not: whosoever sinneth hath not seen Him, neither known Him."

Apostlen lærer os, at selv om vi bør udvise kristelig hensynsfuldhed, så har vi ret til at behandle synden og synderne uden omsvøb og at dette ikke er i modstrid med sand kærlighed. "Enhver, der gør synd, begår dermed også lovbrud, ja, synd er lovbrud. Og I ved, at han åbenbaredes, for at han skulle bære synden; og der er ikke synd i ham. Enhver, der bliver i ham, synder ikke; enhver, der synder, har hverken set ham eller kendt ham."