Peter already ate and drank with some Christians at Antioch, who were Jews and gentiles. But when some Jewish visitors came to Jerusalem to visit; (Acts 10:28; 11:3). These guys from Jerusalem might be some of those who felt every gentile must be circumcised before they could mingle with the Jews.
When these visitors from Jerusalem came, Paul did not refer to them as brethren, but he called them “certain men”. Peter was immediately intimidated, and he avoided eating and mingling with the gentiles, and by doing this, some other brethren were influenced and they did the same as Peter.
Paul could not keep silent about this, he reacted against this hypocritical attitude of preaching one thing and doing another. This was a good proof that Peter exhibited a tendency to compromise his convictions as he really felt intimidated by the belief of these “certain men” from Jerusalem. Paul criticised Peter for his inconsistency, and Paul did rebuke Peter publicly, as this Peter’s act of inconsistency in presenting the gospel has affected a significant number of believers around him.
Paul has the revelation of the true gospel of salvation being attained by faith alone through grace of Christ. Justification comes by believing in Jesus Christ and not be any circumcision. It does not matter who a man is, or where he is coming from.
All that is required is faith in Jesus, and they shall be saved. This was done openly and publicly by Paul in order to dissuade those believers who Peter’s action had affected, and for them to make a correction, moving away from the erroneous belief that circumcision can make a man justified, and establish that gentiles without circumcision can be justified if they believe in Jesus and trust Him for salvation.
This section of Paul’s epistle to the Galatians has generally been described as “Paul’s doctrine of justification”. Upon Peter’s action; discrimination against the gentiles, making them look like sinners who can never be saved because they were uncircumcised. The Jews on the other side thought they were the only set of people who do not need grace for salvation, as they saw themselves as descendants of Abraham, and they have been through the circumcision rite (ritualism), and all gentiles would have to be circumcised before they can be saved.
On the contrary, Paul’s doctrine of justification states that Justification comes by believing in Jesus; (Acts 16:31). Paul publicly stated as he converses with Peter and other believers in Jerusalem, that obedience to work of the law is never going to be enough to make anyone justified, be it Jews or gentile. He further expounded that justification is never the same as forgiveness. Forgiveness is “the fruit of justification”, while atonement is the “basis of justification”.
According to Paul in Galatians 2:15-16, believers can only be justified by faith alone. Christ has completed the whole process of salvation on the cross of Calvary, so the believer’s justification is dependent upon the faith of such a believer. Justification comes by faith alone and not by the ritual of circumcision, human effort or work. “Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ” (Galatians 2:16). The law was written to guide the people before Christ came, but the moment He came and died and rose on the third day, everything changed, and man is now saved and justified by faith alone and not by works.