Now when Peter had come to Antioch, I withstood him to his face, because he was to be blamed; for before certain men came from James, he would eat with the Gentiles; but when they came, he withdrew and separated himself, fearing those who were of the circumcision. And the rest of the Jews also played the hypocrite with him, so that even Barnabas was carried away with their hypocrisy. (Galatians 2:11–13)

Today’s big question: is it ethical to publicly correct a fellow believer?

Jesus discussed the procedure a person should follow when a fellow believer sins against you. In Matthew 18:15–17, He explained that you should first go to that person privately. If he refuses to repent, then you should take one or two others and confront him. If that still doesn’t work, then you are to tell it to the church.

Many Christians believe this is always the pattern to be followed when correcting a fellow believer, but Jesus specifically referred to a situation in which someone sins against you. What if a fellow believer is publicly promoting false teaching? Should we follow Matthew 18 or is there another example in Scripture?

Our passage today shows us that there is another approach to be taken when someone is guilty of publicly promoting false teachings. Peter was leading people astray by publicly siding with the Judaizers—people who taught that justification was not by faith alone because they added circumcision as a requirement for salvation.

Peter knew better. God had already shown him salvation was available to the Gentiles apart from the act of circumcision (Acts 10:44–48). He was present at the Jerusalem Council where the apostles and elders had concluded that a person did not need to be circumcised to be saved. He even testified before them about the Gentiles being saved “by faith” (Acts 15:9). Yet before long, Peter was falling into heresy and had even led Barnabas and others astray.

Since Peter’s sin was public, Paul’s rebuke of Peter was also “before them all” (Galatians 2:14), and rightly so. Had Paul privately rebuked Peter, he may have succeeded in restoring Peter to sound doctrine, but it wasn’t only Peter who was off track. Paul’s public correction of Peter also served to correct all who had been influenced by Peter’s error.

The goal in both approaches is the full restoration of the erring brother. James wrote, “Brethren, if anyone among you wanders from the truth, and someone turns him back, 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 sin” (James 5:19–20; see also Proverbs 9:8–9).

Correcting a fellow believer publicly is never fun, but it is sometimes necessary if we are to obey our Lord.  http://www.answersingenesis.org/articles/2011/03/28/ethical-publicly-correct