I believe Paul was using the word "gentiles", as a "marker." For reason of denoting the difference between Those who were Jew, and those who were not.
A problem I have is the term Jew and its "improper" usage. It seems to be used for the whole nation of Israel, (which I just came to learn recently) not just the "house of Judah" or the southern kingdom . Also "called" a Jew was a resident, no matter where from. Also a Jew, or one who called himself one, but actually of the synagogue of Satan.
It is like the law. The old and new Covenants so different yet many times both just referred to as the law, hence the arguing of apples vs oranges.
It makes me think of Cains lineage, and how many names the same, just to set about confusion. I think by our lack of specificity??? is that a word??? specific-ness, or put another way, laziness, we are, by not being specific with our terms, causing problems ourselves. IDK. I just think the "division" that Jesus came to abolish by making us all one in Him, is getting lost through "the letter" and by not using the spirit of truth. God says "my people are foolish". Don't we just keep proving that right.
No matter what God does, Satan is hard core doing his best to make sure he keeps as many as he can from HIM. This dividing of the NT now.
What are we told about a house divided? Right there in the book being divided. What???
What are we told about no one being any different in Christ, Him breaking down the wall of division, yet right here in this forum you can't even get someone to say " Yes I am a Christian", a follower of Christ, made one in Christ, A Spiritual being, dead to the flesh. Well I think if you are dead to the flesh it doesn't matter WHERE you came from or HOW you were called. Done