In Acts 16, 3, 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. While in Acts 15: 5 But some believers who belonged to the party of the Pharisees rose up and said, “It is necessary to circumcise them and to order them to keep the law of Moses.” In Barnabas and Paul as they related what signs and wonders God had done through them among the Gentiles. (the uncircumcised) James, an elder brother of Jesus, wrote a letter to the Gentles stating Brothers, listen to me. Simeon has related how God first visited the Gentiles, to take from them a people for his name. And with this, the words of the prophets agree, just as it is written, ‘After this, I will return, and I will rebuild the tent of David that has fallen;

I will rebuild its ruins, and I will restore it, that the remnant of humanity may seek the Lord and all the Gentiles who are called by my name, says the Lord, who makes these things known from of old.’Therefore my judgment is that we should not trouble those of the Gentiles concerning being circumcised. Yet the Apostle Paul wrote, in Romans 4; 9- 11 Is this blessing then only for the circumcised or also for the uncircumcised? How, then, was it counted to him? Was it before or after he had been circumcised? It was not after, but before he was circumcised. He received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. The purpose was to make him the father of all who believe without being circumcised, so that righteousness would be counted by them as well

The Gentile did not have to begin practicing it, nor did the Jew have to cease practicing it to be saved. In the Christian age, circumcision is one thing that falls in the realm of Christian liberty.

In Genesis 15, 5: No longer shall your name be called Abram, but your name shall be Abraham, for I have made you the father of many nations. This means the Jews and Gentiles were part of the covenant in short, Gentiles heard the gospel, the Holy Spirit fell upon them where Acts 11: 12,15, 17 And the Spirit told me to go with them, making no distinction. These six brothers also accompanied me, and we entered the man’s house. As I began to speak, the Holy Spirit fell on them just as on us at the beginning. If then God gave the same gift to them as he gave to us when we believed in the Lord Jesus Christ, who was I that I could stand in God’s way?” Calvin wrote, Now, the question is, whether it was lawful for Paul to use a vain sign, whose signification and force was abolished; for it seemeth a vain thing when a departure is made from the institution of God. But circumcision was commanded by God to continue only until the coming of Christ. To this question, I answer that circumcision did so cease at the coming of Christ,

Matthew Henry wrote: 2 Tim. 1:4. 6. That Paul took him and circumcised him, or ordered it to be done. This was strange. Had not Paul opposed those with all his might that were for imposing circumcision upon the Gentile converts? Had he not at this time the decrees of the council at Jerusalem with him, which witnessed against it? He had, and yet circumcised Timothy, not, as those teachers designed in imposing circumcision; why?

The Jews who were in those places for they all knew that his father was Greek and his mother was Jewish. Acts 16; 2 Timothy, the son of a Jewish woman who was a believer, but his father was a Greek. Believer Bible Commentary wrote, Acts 16:3 (BBC): Paul, Silas, and Timothy were going forth on evangelistic work. Their first contact would frequently be with the Jews. If these Jews knew that Timothy was not circumcised, they might refuse to listen, whereas if he were, there would be no possibility of offence on this score. Since it was entirely a matter of moral indifference and not of doctrinal importance, Paul submitted Timothy to this Jewish ordinance. He was made all things to all men that he might, by all means, save some (1 Cor. 9:19–23). Though free from all, I have made myself a servant to all, that I might win more of them. To the Jews, I became as a Jew, to win Jews. To those under the law, I became as one under the law (though not being myself under the law) that I might win those under the law. To those outside the law, I became as one outside the law (not being outside the law of God but under the law of Christ) so that I might win over those outside the law. To the weak, I became weak, that I might win the weak. I have become all things to all people, and by all means, I might save some. I do it all for the sake of the gospel, that I may share with them in its blessings.

The interpretation that Paul’s circumcising of Timothy was to gain an audience for the gospel with the Jews seems to be strongly implied by the words, and circumcised him because of the Jews Likely first question Jewish people would asks him if was circumcise

Dr John Gil wrote, that the apostle used circumcision not as a duty of the law, because of the Jews who were in those quarters; not the believing ones, Acts 16:3 (ENTVIIII): to teach in their synagogues, nor would they hear him out of them; wherefore having a mind to take Timothy with him to be assisting to him in the preaching of the Gospel, in point of prudence he thought it proper to circumcise him, that he might be received by them, and be the more acceptable to them; who would otherwise have taken such an offence at him, as not to have heard him: thus the apostle to the Jews became a Jew, that he might gain and save some, 1 Cor. 9:20 for they knew all that his father was a Greek; and that therefore he was not circumcised: for a woman might not circumcise, because she was not a fit subject of circumcision herself; though in case of necessity circumcision by women was allowed of. Moody Bible wrote Paul had Timothy circumcised not as a precondition for salvation but as an outward sign of the Abrahamic covenant. Paul would never compromise the gospel. As the Scriptures declare, If possible, so far as it depends on you, be at peace with all men.