Moreover if your brother sins against you, go and tell him his fault between you and him alone. If he hears you, you have gained your brother. (Matthew 18:15, NKJV)
The sin under consideration in this verse is personal in nature (“against you”). Its private nature is necessarily implied in the instruction Jesus gives, “go and tell him his fault between you and him alone.” The sin is not generally known, and is to be privately discussed. Christ’s command also implies the one who sinned may not even know he has sinned against his brother, since Jesus said to “tell him his fault…” The manner of this initial discussion is informative and persuasive. That is, the sinner needs to “hear” that he has sinned, as well as how to remedy it through repentance (Acts 8:22). Damage is done when private sins are made public. Gossip, backbiting and rumor-mongering may begin from a failure to keep private sins, private. Remember, the goal is to “seek the one that is straying,” not slay him because he has wandered from the Shepherd (Matt. 18:12).
19 Brethren, if anyone among you wanders from the truth, and someone turns him back, 20 let him know that he who turns a sinner from the error of his way will save a soul from death and cover a multitude of sins. (James 5:19–20, NKJV)
This Bible passage enjoins upon faithful Christians the task of rescuing a struggling, sinning Christian from spiritual death. It forever exposes and opposes the false teaching of “once saved, always saved.” Here, the soul that needs saving is a Christian who: (1) Has wandered from the truth. We must walk in the truth to be secure in our salvation (Jno. 10:27); (2) Needs turning back. The person is headed in the wrong, spiritual direction; His present way is “error.” You see, there really is only one way that leads to life (Jno. 14:6); (3) Has sinned. The person is “a sinner,” “in error” and in “death.” He/she is lost. You see, doctrine (teaching) affects salvation. False doctrine is error; a wandering from the truth. Wandering from the truth into error is a real danger. When it happens, the spiritually strong must become first responders, trying to save a soul from death (Gal. 6:1). In what more worthy endeavor can you participate? “He who wins souls is wise” (Prov. 11:30).