Peter and Paul were brothers in Christ and friends.  They supported each other and encouraged one another’s ministry (Galatians 2:7-9).  However, when Peter (‘Cephas’ in Greek) came to the missionary base in Antioch in Syria, He was so absorbed with his ministry to the Jews that he did not want to be seen with Gentiles.  

Paul saw that Peter was at risk of undermining the gospel because of a wrong fear.  Some Jewish believers thought that, in order to be fully accepted by God, the old Jewish rule of circumcision still had to be kept.  They insisted that Gentiles must be circumcised; otherwise they could not be proper Christians (Acts 15:1-11).  Initially, Peter taught that Christ had fulfilled all of the law and that those rules were now obsolete.  But when important Jewish believers came to Antioch from Jerusalem, they pressurised Peter into staying away from uncircumcised Gentiles.
 
Peter was afraid that he would lose his good reputation among Jewish-born Christians.  So he placated the visitors and local Jewish people by not eating with Gentiles because they were not ceremonially clean.  But Paul knew that this was wrong and divisive.  Because of Peter’s reputation, his wrong behaviour infected even senior leaders like Barnabas.  So Paul took the unusual step of rebuking Peter.  The integrity of the gospel and the honour of Jesus Christ were far more important than Peter’s desire to be accepted by his fellow countrymen, or his wrong idea that more Jews would be converted if he dissociated from Gentiles – even though God had already shown him that was wrong (Acts 11:1-18).
 
‘Fear of what people may think’ is a terrible disease.  Peter showed it spectacularly when he denied Jesus before His crucifixion (Matthew 26:69-75).  But it was still in his nature.  Perhaps even his blustering, larger-than-life personality was a mask for his inner insecurity.  ‘Wanting to be liked’ leads many astray and has often caused believers to change the gospel to something which does not have God’s blessing and cannot save.  Controversy is not nice and personal challenge feels offensive.  But what matters more: protecting the purity of the gospel, through which people can be saved for eternity, or being liked and accepted during your lifetime?  We would like to have both, but often that is not possible.  Which do you choose?