Paul wanted Timothy to accompany him, and he took him and circumcised him because of the Jews who were in those places,
for they all knew that his father was a Greek. (Acts 16:3)
At the first leg of Paul’s second missionary journey, he stopped at Lystra. There, he recruited Timothy as his protégé, and Acts 16:3 says that Paul circumcised him (or at least Paul had Timothy circumcised if he did not get his own hand dirty). This comment, however, might simply pass simply as a factual reporting, a nice-to-know-and-let’s-move-on kind of fact. However, reading what happened just before this event would inevitably raise at least one question.
In Acts 15, Paul had just debated the Jews who came to Antioch from Judea about the merit of circumcision for one’s salvation. The Jews insisted that circumcision was necessary for salvation (Acts 15:1). Paul, however, insisted that the snip-snip was unnecessary. None of them was willing to back down. So, Paul brought the matter up (or south) to Jerusalem Council. The apostles and the leaders at Jerusalem would need to settle this matter swiftly: do Gentiles need to be circumcised to secure their salvation? The council made a historic decision that Gentiles did not need to become Jews (or proselytes) in order to receive salvation in Jesus. This was a big win to the Gentiles. So, Paul returned to Antioch with affirmed and endorsed conviction that circumcision is indeed not meritorious for one’s salvation.