How far would you go in accommodating and fellowshiping with Christians with radically different cultural customs? Sadly I have seen many instances where people have asked the opposite question: what is the minimum amount of difference that would justify me not having anything to do with them?
This is the question at hand in Acts 21:17-26. Paul and companions arrive in Jerusalem and meet James and the other elders. They get a warm welcome. They were brining the gift of money from the Gentile churches for famine relief, but Luke concentrates more on the report of what God has done among the Gentiles. Everyone praised God when they heard all about it.
But there was an issue - and it seemed on the surface to be a big one. We read it in v20-21. Many thousands of Jews in Jerusalem had come to believe that Jesus was the Christ. They were committed to Christ but zealously Jewish in their cultural practices and traditions. They had heard that Paul taught Jews living eslewhere in Gentile provinces to turn away from Moses and from those cultural practices they held so dear.
So here is the question: are there two, incompatible, doctrinal positions? The Jewish church teaching salvation through adherence to Moses and Mosaic law practice, the Gentile churches teaching salvation by grace?
And another, moral, question in v24: people have heard that you don't live according to what God revealed and that you aren't interested in obeying the Old Testament.
The answer is that both James and Paul had already agreed that salvation is by grace and not by works in Acts 15. Therefore this is not a discussion about how you get saved. It is a discussion about customs that some people still held to be very important to them. Therefore, as far as Paul was concerned, they fell into the category of "matters of indifference". If the argument had been that people were saved by these customs we would have seen a very different response.
How does Paul deal with matters of indifference? He entirely goes along with them for the sake of relationship. Some might think he purjures himself by participating in a purification rite that he knows contains no significance for salvation or discipleship. Except that for those he goes with and pays for, it is a matter of conscience, and he is keen to not trample over it. This is "becoming like the people I am with in order to win some; like a Jew to the Jews, like a Gentile to the Gentiles."
Here is the principle: forebear with others in matters of indifference. Participate with them. Be friends with them. Encourage them.
But one more thing needs to be said: we need to be careful to distinguish what are matters of indifference and what aren't. I think ther are twin dangers: elevating to primary importance things that aren't - like style of meetings - and thereby refusing to have fellowship with people we should; or, demoting things that are of first importance - like core doctrines - to secondaries for the sake of wanting to be friends with everybody.
Unless we are sure not only what we believe, but why we do, we won't know how to make that distinction. Last Sunday I preached on justification by faith and am certain that a good number of people had no idea at all that Protestants and Catholics believe completely different things about the core doctrine of how we are saved. The reason: because they don't know why they believe that they are saved by faith, and have no historical or doctrinal teaching on why it is a first-order error to teach that we are saved by works.
The lesson from Paul is to bend over backwards to accommodate cultural practice and custom, but not wrong doctrine.