​John 7:35 | 
Then said the Jews among themselves, Whither will he go, that we shall not find him? will he go unto the dispersed among the Gentiles, and teach the Gentiles?

Gentile (from Latin gentilis 'of or belonging to the same people or nation', from gēns 'clan; tribe; people, family') is a term that usually means 'someone who is not a Jew'. ... The original words goy and ethnos refer to "peoples" or "nations" and are applied to both Israelites and non-Israelites in the Bible.

The one thing the churches left out of the whole  gentile doctrinal scheme is that by definition gentile also apply to Israelites.
yes indeed, an israelite that live among gentiles living and practicing the way of life of another nation is regarded as a gentile as well.

John 7:35 |
Then said the Jews among themselves, Whither will he go, that we shall not find him? will he go unto the dispersed among the Gentiles, and teach the Gentiles?

A very good instance is in this verse here, the jews said will he go among the dispersed among the gentiles?
the dispersed are israelites >> see James 1:1<< gentiles cannot be dispersed among themselves where they actually dwell anyway. 
Then they proceed to say to teach the gentiles, you see here the dispersed who are jews are being called gentiles. 

THE WHOLE TRUTH CONCERNING JEWS AND GENTILES 

NO DIFFERENCE BETWEEN JEWS AND GENTILES

Romans 9:24
“Even us, whom he hath called, not of the Jews only, but also of the Gentiles?”
“As he saith also in Osee, I will call them my people, which were not my people; and her beloved, which was not beloved.”
“And it shall come to pass, that in the place where it was said unto them, Ye are not my people; there shall they be called the children of the living God.”
“Esaias also crieth concerning Israel, Though the number of the children of Israel be as the sand of the sea, a remnant shall be saved:”

Ephesians 2:12
“That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world:”

Romans 9:4
 “Who are Israelites; to whom pertaineth the adoption, and the glory, and the covenants, and the giving of the law, and the service of God, and the promises;”

What do we have here? Paul is clarifying his stance here, he is removing doubt by saying we're not calling Jews only but of gentiles. The best part is when he explain the calling of the gentiles fulfilled prophecy given by Oseah a prophecy which shows where israel at one point in time would no longer be God's people, to afterward come back and call Israel his people again, proving further these gentiles who were living as other nations here were indeed israelites. 

The book of Ephesians 2:12 make a quick work out of modern Christian doctrine, so pay attention. 
It states you (gentiles) were without the Messiah, being Aliens from the " commonwealth" of Israel. 

commonwealth is a shared interest belong to a group a country. As you can see Paul is telling these gentiles, you were alienated from what belong to you as well, which is the covenant of promise, which we all know only belong to Israel. see Romans 9:3


Now that we clear that those particular gentiles being called were lost Israelites, we can conclude that no difference between Jews and gentiles was a call of truce that Paul was sending to remind both parties they were after all the same people.