The Israel "of Israel"
For they are not all Israel who are of Israel (Romans 9:6)
It seems to be saying that there is a part of Israel that is special. The bigger group - physical Israel, has a special group - "Spritual Israel" within it. Some of "Spritual Israel" are OT saints and some are those who are responding to the Messiah at present. All of this group "Spiritual Israel" have faith. Not all of physical Israel have faith, they are not all "prince of God."
This drawing so far has nothing to do with gentiles, but only with "Israel." I have an expanded version of this drawing that I will post tomorrow. But this is how I see the specific pharse "For they are not all Israel who are of Israel."