For me, as I suspect for many Jewish people, an awareness of the contradictions that lie at the heart of my Jewishness is never far from the surface but, when push comes to shove, as it inevitably does, and as with all matters concerning race, the choice is not ours to make; it will be made by racists, on internet message boards, in parliamentary debates, on Twitter or Fox News, in the White House, in online manifestos and marching through universities with flaming torches held aloft.