Why do we think there are differences between ethnic Jewish Christians and Gentile Christians? (Eph 3:6)

Ephesians 3:6 presents us with two issues. One is the oddity of words compounded with σύν. The other is with the theological implications of Jews and Gentiles being “joint heirs ... fellow members of the body ... and sharers together in the promise in Christ Jesus.” The mystery of the gospel is the combining of these two people–groups. Do you separate them in your mind to any degree? Why? Whatever we believe, we have to make sense of these three compound words.