Why does Paul circumcise Timothy?

In the earlier chapter, Paul fought against the requirement of circumcision in the previous chapter (Acts 15; c.f. Ga. 5:2). However, here in the next chapter, he quickly circumcises Timothy?

Paul circumcised Timothy for a missiological principle. While circumcision doesn’t ultimately matter (1 Cor. 7:19), it makes sense that Paul circumcised Timothy, because he was trying to fit in with the Jews, which was a theme of Paul’s ministry (1 Cor. 9:20). Paul didn’t think that circumcision was necessary for salvation (Acts 15:1); he did think it was necessary for evangelism in the Jewish culture. Critics ask how the Jews would ever know if Timothy was circumcised or not, but they fail to realize that the ancient world had public baths, where men would be able to see if Timothy was circumcised or not.