In Acts 16, Paul has Timothy circumcised. "There they met Timothy, a young disciple whose mother was a Jewish believer, but whose father was a Greek. 2 Timothy was well thought of by the believers in Lystra and Iconium, 3 so Paul wanted him to join them on their journey. In deference to the Jews of the area, he arranged for Timothy to be circumcised before they left, for everyone knew that his father was a Greek."
However. the preceding chapter in Acts 15, is all about the leaders of the Church, James, Peter and Paul agreeing that Gentiles do not need to be circumcised:
13..."James stood and said, "Brothers, listen to me. 14 Peter has told you about the time God first visited the Gentiles to take from them a people for himself. 15 And this conversion of Gentiles agrees with what the prophets predicted. For instance, it is written: 16 'Afterward I will return, and I will restore the fallen kingdom of David. From the ruins I will rebuild it, and I will restore it, 17 so that the rest of humanity might find the Lord, including the Gentiles -- all those I have called to be mine. This is what the Lord says, 18 he who made these things known long ago.' 19 And so my judgment is that we should stop troubling the Gentiles who turn to God, 20 except that we should write to them and tell them to abstain from eating meat sacrificed to idols, from sexual immorality, and from consuming blood or eating the meat of strangled animals."
It doesn't make sense, that after all of them agreeing in no circumcising necessary for Gentiles, that suddenly Timothy needs to be circumcised.