Christianity is not a nationality, a person who is not baptised is not Christian. There are many cases of atheists, even of Jewish converts who converted abroad or non-orthodox and Jews who fail to proove their Judaism after Aliyah, who are registered as Christians. A friend of mine protested against it but was told he is Christian because he is not Jewish and was born in New Zealand.
U.S., allies conduct 1 air strike in Syria and 11 in Iraq against ISIS militants (Reuters)
from the article: Israeli author Yoram Kaniuk asks court to cancel his 'Jewish' status