Never believe that anti-Semites are completely unaware of the absurdity of their replies. They know that their remarks are frivolous, open to challenge. But they are amusing themselves, for it is their adversary who is obliged to use words responsibly, since he believes in words. The anti-Semites have the right to play. They even like to play with discourse for, by giving ridiculous reasons, they discredit the seriousness of their interlocutors. They delight in acting in bad faith, since they seek not to persuade by sound argument but to intimidate and disconcert. If you press them too closely, they will abruptly fall silent, loftily indicating by some phrase that the time for argument is past.
This quote is attributed to Jean-Paul Sartre. I guess this is from his book "Anti-Semite and Jew".
However, I don't think it matters what is the source of this quote. What matters is that this is one of the good descriptions of what the antisemites and today's anti-Zionists or anti-Israelis as they call themselves do.
Well, except of the dash.