If we were to be very gracious and exempt a million Jewish people who believe Jesus is the Messiah, even though they consider themselves Jews and the rest of Judaism does not reject them unless they are judged individually as having "converted" (which isn't the same as merely believing Jesus is the Messiah), that hypothetical definition would only get us so far as to define "Jew" by religion and not ethnicity and would not implicate all such "Jews" (men, women, and children) as being either nonethnic or criminal.

In particular, Ashkenazi Jews have Jewish heritage dating back to Temple Jews (Ioudaioi) even if there was some immixing. If Americans can tell Jews they're not Jews, then Jews can tell Americans they're not Americans (which is exactly what you imply you don't want them doing); so your argument "not Jews" contains seeds of your own destruction at the hands you claim to despise. That is you're arguing exactly as you say a Jew argues.

So the evidence that the Ashkenazi arose at some point in history from a people without any Jewish birth/conversion integration is totally missing. At the same time, simple surname evidence indicates that most all named any form of Cohen (note, Khazarian "Kagan"), Katz (Kohen-Tzedek), Levi, or Sacerdote have heritage back to the Biblical Levi, and several names have heritage back through second temple Judah to the Biblical Judah, such as Abravanel, Berdugo, Charlap, Dayan, Epstein, Horowitz, Luria, Shaltiel, Spira, Yahya. Netanyahu and Schneersohn claim heritage from gaon Elijah Zalman, others from Rashi or Isaac Luria. Obviously many Ashkenazim do not have such extensive genealogies handy, and many with the best surnames don't have the genealogy handy either, but this much would suffice for any nation to claim continuous heritage against the claims of outsiders. DNA evidence agrees.

1 Thess. 2:15 "contrary to all men" is spoken by a Jew to other Jews about a different subset of "the Jews" "in Judaea" (14), not about all Jews, nor even about all unbelieving Jews. Here are some Biblical descriptions that don't and that do apply to all Jews generically.

I appreciate that you are mostly moderate and not stretching the criticism to those who are innocent of it (e.g. children). You are mostly keeping good pace and not falling into traps that others have who deal with this subject. If you were able to offer historical evidence comparable to the above to advance the thesis that one nationality (yours) has the right to deny the nationality of another ("Jews'"), you might get somewhere; but seeing as nobody ever does then it might be wiser to tone it down and stick to actual facts.