Jewish Christians did not oppose people who were not Jews converting to Christ. Jews led people to the living God before Christianity existed (see Matthew 23:15). That process produced proselytes.
For example, if an idol worshipper (a) underwent careful indoctrination, (b) expressed faith in the teachings by becoming a proselyte, and (c) then became a Christian, that was wonderful. However, such a person must be a proselyte to Judaism before he/she became a Christian (see Acts 11:1-3 and 15:1-5).
When Paul wrote the book of Romans to Christians in the city of Rome, there were Jewish and gentile Christians. The background of each group was distinctly different!
In chapters 1-11 Paul stressed it always was Gods intent to save people who were not Jews (see Genesis 12:3). While that is welcome news to most of us, it was not welcome news to many first century Jewish Christians. One of their chief complaints: How can people who did not know Who the living God was suddenly behave and function as Gods people?
In chapters 12-15, Paul described what a gentile Christian would look and act like in the environment of Rome. Rome was then the seat of power and the center of commerce in the Mediterranean world. How would a Christian man or woman exposed to all Romes influences behave and act?
To me that continues as a relevant question. We often live in corrupt communities in a corrupt nation. Surely there are worse places. However, there are improvements we all would like to see here.
Sometimes Christians look so much like the part of society who does not know God, we cannot tell the Christian from the person who is not a Christian. Aside from the Christian going to church, they often are quite similar in behavior and goals. I am not talking about artificial differences. I am talking about godly dedication to stable marriages and homes, or not being sexually active outside of marriage, or not being greed led or power ruled.
Our society needs to see what a Christian looks like. Can it look at you and see?
Link to other Writings of David Chadwell