Do not speak evil of one another brethren. (James 4:11)
“Do not speak evil” covers more than slander, extending to any form of speaking against someone, including truth, if it is delivered in a harsh and unkind way. Speech is evil when it is motivated by the desire to harm others or to exalt oneself.
Sin cannot be understood or described without reference to self-centeredness. “The flesh” is self-focused. Carnality is self-expression in behalf of a person’s own interests.