Paul said this, and Timothy understood the application. In 1 Corinthians 9, Paul is defending his right to be paid for his labor in the kingdom. In this context, he mentions an often misunderstood passage.
“For though I am free from all men, I have made myself a slave to all, so that I may win more. To the Jews I became as a Jew, so that I might win Jews; to those who are under the Law, as under the Law though not being myself under the Law, so that I might win those who are under the Law; to those who are without law, as without law, though not being without the law of God but under the law of Christ, so that I might win those who are without law. To the weak I became weak, that I might win the weak; I have become all things to all men, so that I may by all means save some. I do all things for the sake of the gospel, so that I may become a fellow partaker of it” (1 Cor. 9:19-23).
Some have used the idea of “becoming all things to all men” with great liberty. Paul clearly mentions being “under the law of Christ.” He is not saying that he acted outside the boundaries of the gospel. He is referring to doing the things he could to make his presence and speech more acceptable to these different groups. He did not want to do anything that would hinder the message of the gospel.
Timothy understood this because of what happened in Acts 16:1-3. Here they were introduced to Timothy, and Paul wanted him to come with them on their journey. They know his father is a Greek, so they have Timothy circumcised before they leave. Paul said in 1 Corinthians 7:19, “Circumcision is nothing, and uncircumcision is nothing, but what matters is the keeping of the commandments of God.” Poor Timothy! What is happening in Act 16? He is becoming all things to all men. He would not have been able to enter into the Jewish synagogues or teach Jews if he was not circumcised. To the Greeks, this was a strange mutilation of the body and culturally frowned upon. He did it for the sake of the gospel. So, the ordeal that Timothy endured was a direct application to making yourself a slave to others.
We need to consider our actions in evangelism and personal work in this light. If I could change a few things about how I present myself (WITHOUT COMPROMISING THE LAW OF CHRIST), then I might become more effective in gaining access into a particular group. It would be for the sake of the gospel. Paul is doing all he can to be able to have an opportunity to present the gospel. He has made himself a slave to others in their need for the gospel. What is misunderstood and overlooked is Paul’s devotion and humility to serve others.