“And the tongue is a fire, a world of iniquity. The tongue is so set among our members that it defiles the whole body, and sets on fire the course of nature; and it is set on fire by hell.”
The tongue is so set among our members that it defiles the whole body,
The words “so set” means to ordain, appoint, place, put. The carnal Christian negative attitudes constitute his tongue so as to defile his whole body. It is the constitution of the tongue to defile by what it says.
Ecc 5:6, “Do not let your mouth cause your flesh to sin, nor say before the messenger of God that it was an error. Why should God be angry at your excuse and destroy the work of your hands?”
Mt 15:10, “When He had called the multitude to Himself, He said to them, ‘Hear and understand: 11 Not what goes into the mouth defiles a man; but what comes out of the mouth, this defiles a man.’”
and sets on fire the course of nature;
The word “course” means something that orbs like a wheel. Wherever the tongue goes, it keeps setting (present tense) the orb (wheel) of nature on fire. The tongue causes a great commotion by a pattern of action and reactions to people.
The tongue can establish a pattern of great conflagration and conflict among Christians.
Evil thoughts produce evil expressions, and those evil expressions produce more evil expressions. It is a vicious cycle constantly ignited by the tongue. The tongue gives it life. The tongue starts a cycle of sin that eventually results in a conflagration of evil.