My mothers, mother, mothers family were Jews and they migrated from Michigan to Arkansas sometime in the 1920’s. Somehow or another, they stopped praticing Judaism and were converted to Christianity. Thru the generations some members of the family have praticed Christianity while others were more secular. Our roots were all but forgotten untill my generation. I understand that, Rabbi Lewis plainly stated, " Judaism is not defined by practice. If you were born to a Jewish mother you are Jewish. Even if you don’t practice. Even if you don’t believe in God. Even if you declare yourself non Jewish – you still are." The question is, although different members of my family, including my mother have somewhat practiced Christianity, am I still Jewish?
Shalom The Halacha (Jewish law) hasn't changed since my last answer. It is true that for some Halachic requirements, a person whom converted into Christianity will be disqualified from, (for instance see SA YD 2) It is also true that you will have to prove your Jewish roots beyond any doubt. I must add that in some cases where a person has converted out of the faith, the Beth Din (Jewish court) based on Rabbinic law, will require a "symbolic conversion" back into Judaism to symbolize the new stage in his life. (SA YD 268, 12) Strictly speaking however, a Jew remains Jewish no matter what. (Tur EH 44)