Among the more serious of the evils that had developed among the Corinthian believers, was that of a return to many of the debasing customs of heathenism. One former 304 convert had so far backslidden that his licentious course was a violation of even the low standard of morality held by the Gentile world. The apostle pleaded with the church to put away from among them "that wicked person." "Know ye not," he admonished them, "that a little leaven leaveneth the whole lump? Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened."

Blandt de mere alvorlige onder, der havde udviklet sig blandt de korintiske kristne, var en tilbagevenden til hedenskabets fordærvede skikke. En, der tidligere var blevet omvendt, var gledet så langt ud, at hans utugtige liv var en krænkelse af selv den lave moral indenfor hedningeverdenen. Apostlen pålagde menigheden at skille sig af med "det onde menneske." Ved I ikke," formanede han dem, "at en smule surdej syrer hele dejen? Rens den gamle surdej ud, for at I kan være en ny dej, da I jo er usyrede."