Paul's second missionary journey began with a regrettable start. A heated argument with fellow evangelist Barnabas causes the two men to go their separate ways. Paul then chooses to take Silas on his evangelistic trip (Acts 15:36 - 41). The pair travel from Syrian Antioch to Tarsus and then to Lystra. It is in Lystra that he meets a young man named Timothy. Impressed by his character, he decides to take him along on the rest of his journey. He first, however, has him circumcised.
". . . there was a certain disciple named Timothy, son of a certain Jewish woman who believed, but his father was a Greek. He was recommended to Paul by the brethren in Lystra and Iconium, and Paul desired to take him with him; but because of the Jews in those places, he took him and circumcised him . . ." (Acts 16:1 - 3, HBFV throughout).
Timothy's Jewish mother meant that he, too, was considered a Jew. Both his mother Eunice and grandmother Lois taught him the Old Testament scriptures that were, "able to make you wise unto salvation through faith, which is in Christ Jesus" (2Timothy 3:15). So why wasn't he circumcised when Paul met him?
Sign of a Jew
At the time of Timothy's birth it is likely his gentile (Greek) father refused (or maybe forgot) to have his son circumcised on the eighth day as was traditional (Leviticus 12:1 - 3). Jews at the time would not circumcise a male baby if it were against the wishes of his non-Jewish father (Jamieson, Fausset and Brown Commentary). That said, the father of Timothy certainly allowed his son to be raised in the Jewish faith.
Why?
We find a clue at the tail end of Acts 16:3 as to why Paul had Timothy circumcised. Luke, the writer of Acts, states, ". . . for they (the Jews) all knew that his father was a Greek." The apostle did what he did for the sake of expediency.
Paul's method for evangelizing a particular area was to first visit the local synagogues (see Acts 13:5, 14, 14:1, etc.) and preach the gospel to Jews and proselytes (Romans 1:16, 2:9 - 10). The apostle felt, given the zealously-held prejudices the Jews harbored against those not circumcised, that having Timothy undergo this procedure would circumvent these biases and allow both of them to have (at least initially) trouble-free access to synagogue members.
"Now, for Apostle Paul to travel among the Synagogues with a companion in this condition (uncircumcised), - and to attempt to convince the Jews that Jesus was the Messiah, when his associate and assistant in the work was an "uncircumcised Heathen," - would evidently have been to encumber his progress and embarrass his work . . .
"Had Timothy not been circumcised, a storm would have gathered round the Apostle in his further progress. The Jews, who were ever ready to persecute him from city to city, would have denounced him still more violently in every Synagogue . . ." (Life and Epistles of Apostle Paul, chapter 8).
Conclusion
Paul decided to take Timothy, a young man around 33 years old, with him as his Christian character was evident to all (Acts 16:2). The Apostle Paul's prudent decision to have him circumcised led to not only the creation of an effective evangelist but also the closest and most trusted friend he would have during his long ministry!