It is exactly this attitude that made Jewish integration next to impossible.
Jews were always welcomed with open arms in the Catholic Church and there were many converts from Judaism in history. Of course, there was a difference between Catholics and Protestants in this regard. For example, in pre-war Catholic Poland, Poles considered Jewish converts to be Poles, and Jews who decided to cling to their religion were considered Polish citizens of abrahamic confession. In pre-war protestant Germany, Germans considered Jews to be "untermensch" and murdered them regardless of their religious afiliation or lack of it.
According to you, even I, born in Poland and raised as a Catholic, lost the right to claim that I am Polish.
Really? Do you completely reject Catholicism and Catholic church? I hope not.
There's an absolutely brilliant book by Stanisław Krajski...
... in which the author explains abundantly why you cannot really consider yourself Polish and remain outside the One And Only, Holy, Roman and Apostolic, Catholic Church.
Was anything ever Mary's fault?
No, of course not. Don't be ridiculous.