[SolidWood]

Wrong.

It is primarily an ethnic category and understood as such by by Jewish law, Israel and most Jews (and non-Jews) in the world.

Read up on what defines a Jew.

Your friends who converted to Christianity are still ethnic Jews, if not by cultural attachment then still by blood.

[Rashputin]

You need to explain this to his former friends. They do not agree with you one little bit.

I've read up on what defines a Jew and as far as I've ever found there's no DNA marker like there is with other ethnic groups. My wife is Cherokee, for example, and if need be a blood test proves she's a Native American. I gather they can now narrow it down to which tribe these days if anyone cares.

I've never read of anything similar regarding the Jews but maybe you could point it out for me.

You're free to define yourself and your fellow Jews however you like but it comes down to hot air IMHo without the same sort of DNA proof other ethnic groups rely on.