Handling doctrinal error in the life of a fellow believer.
If he is ignorant teach him the truth.
II Tim. 2:23-26, But foolish and unlearned questions avoid, knowing that they do gender strifes. And the servant of the Lord must not strive; but be gentle unto all men, apt to teach, patient, In meekness instructing those that oppose themselves; if God peradventure will give them repentance to the acknowledging of the truth; And that they may recover themselves out of the snare of the devil, who are taken captive by him at his will.
If he persists in error, rebuke him.
Titus 1:10-14;
Galatians 2:11, But when Peter was come to Antioch, I withstood him to the face, because he was to be blamed.
If the error continues, avoid him.
Rom. 16:17-18, Now I beseech you, brethren, mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them. For they that are such serve not our Lord Jesus Christ, but their own belly; and by good words and fair speeches deceive the hearts of the simple.
Separate yourself from him.
Continue to treat him as a brother and not an enemy or heathen. The goal is repentance and restoration.
(Lev 19:17) Thou shalt not hate thy brother in thine heart: thou shalt in any wise rebuke thy neighbour, and not suffer sin upon him. End 1/19/11