Paul was (sometimes) against Circumcision
In Acts 15, Paul and Barnabas were involved in one of the biggest controversies of the early church. The issue was whether or not someone could be a Christian without circumcision. After much discussion, the Jerusalem Council affirmed the message of Peter and Paul, that God’s grace extends to Gentiles as Gentiles. In other words, circumcision was deemed as unnecessary to be a part of the church.
This decision was confirmed by Paul in Galatians 5:2-3, 6:
Behold I, Paul, say to you that if you receive circumcision, Christ will be of no benefit to you. And I testify again to every man who receives circumcision, that he is under obligation to keep the whole Law…. For in Christ Jesus neither circumcision nor uncircumcision means anything, but faith working through love.
Earlier in Galatians Paul recounts how certain Jews compelled Titus to be circumcised (Gal 2:3). Yet, Paul would not yield to their wishes so that the truth of the gospel would not be diluted (Gal 2:5).
So, it appears Paul is steadfastly against circumcision thus far. Yet, in Acts 16:1-3 we see a bit of a different picture.
Paul came also to Derbe and to Lystra. And a disciple was there, named Timothy, the son of a Jewish woman who was a believer, but his father was a Greek, and he was well spoken of by the brethren who were in Lystra and Iconium. Paul wanted this man to go with him; and he took him and circumcised him because of the Jews who were in those parts, for they all knew that his father was a Greek.
How are we to think about this time (after the Jerusalem Council ) where Paul circumcises Timothy? Was Paul abandoning his standards?
One helpful piece of information is that while Titus was a Greek, Timothy’s mother was Jewish, which means that he would have been considered ethnically Jewish. If Timothy was to accompany Paul on his missions to the Jewish community as an uncircumcised Jew, this would have been unnecessarily offensive.
Hence, we see here a clear application of the principle in 1 Cor 9:19-23, “…To the Jews I became as a Jew…” Circumcision was not something absolutely forbidden by Paul, unless it was viewed as having a role in meriting acceptance into the Church.
To Paul, it was grace alone through faith which gave believers a relationship with the Messiah. However, if one understood that reality, then Paul was not interested in telling Jews they should not observe their customs. In other words, Paul was only against circumcision if it misconstrued the pure message of the gospel of faith in the Messiah.