"Yes, BenS, that's exactly what I'm saying. I don't care whether you like it or not; that's Halacha. Just 'cause you don't like it doesn't make you an authority, and doesn't make it not so"

This is absolute lunacy. You cannot claim an opinion as fact - and 'Jewish laws' are not real laws. They don't apply to me and YOU (or other Jews) don't get to decide who they apply to. I don't care whether you like it or not, you claiming it does not make you an authority and it doesn't make it so. You can claim it's 'Jewish law' until you're blue in the face but that boy in the example given has never even heard of Jewish law, didn't sign up to it and yet you're saying he's bound by it? Bollocks.

" Ben, if you are Gentile, then of course someone telling you that you're Jewish over and over wouldn't make it so."

We're arguing over the definition of Jewish here. The 'Jews' have decided what it means to be Jewish and apparently they're applying it to whomever their laws (opinions, actually) say is a Jew - regardless of what the recipient thinks. If my mother is Jewish then someone telling me over and over does NOT make me Jewish by any rational definition. If I don't follow the religion, don't follow the custom then in NO RATIONAL WAY am I a Jew.

It makes as much sense as me defining everyone with the letters 'Rob' in their RD username - and all their descendents in perpetuity - a Snogwart. There you are, you're a Snogwart. You can't say you're not because, by very definition, you are. No point arguing. You might not stand on one leg on Wednesdays like Snogwarts are supposed to and you might not worship the great Snoggle in the sky, but you're still a Snogwart. And so are your kids. And their kids. Forever. For this is the law of the Snoggle - as old and as true as the sky.

Do you see how stupid that is?

" Citizenship in a nation is not just a matter of your individual opinion or mine; it's a matter of the legal system in place for that nation."

But you're TELLING people what nation they're in, even when they have no desire, wish or inclination to be in it. It's like someone being born in America to an American family and yet being called English because their great great great grandmother was. It's nonsense.

"Now please, Ben, if I am wrong when I say that the matrilineal heritage of Torah and Mitzvoth is what unites all Jews including the atheistic ones, then please tell us what does."

The onus is on you to prove this in a sensible manner, not on me to disprove it. You've just claimed it and given your reasoning as 'because I say so'. Doesn't work like that. You're a Snogwart, you should know this.

"Why would we ever even call an Atheist a Jew if there isn't something which unites him with those Jews who are more religious than he is?"

I have no idea. This is my point. You've decided there's something that unites this person with Jews, decided it applies to them and then called them a Jew. In the example I gave above, that lad (born in Tunisia to Muslim parents) is still a Jew according to you. United by Torah and Mitzvoh to all the other Jews, apparently, despite him never even having heard of them. I don't know why you'd want to call those who don't identify themselves as Jews, Jews, but you seem hell bent on doing so.

"Your point about Vegans for Beef is fine, but if the same principle were applied here, wouldn't an Atheist with matrilineal Jewish ancestory be a non-Jew?"

Ask them.