I like this article (short and to the point), “Could you prove you’re a Christian?” written by Keith Manuel (Mar 18, 2008), taken from a Baptist site.
Here’s the introduction: “A recent article in The New York Times discussed the difficulty facing some American-born Jews, now living in Israel, to prove the authenticity of their heritage. One young woman went with her fiancé to the Tel Aviv Rabbinate to register to marry. This governmental court asked her to prove she was Jewish.
If a court of law asked you to prove you were a Christian, how would you do it?”
(The link above, should take you to the full article.)