Last Friday evening I put on a kippah and walked half an hour across Budapest to the Keren Or synagogue maintained by the Budapest Chabad. After violent attacks on Jews in German streets, the leaders of Germany’s Jewish community warned Jews last month not to wear a kippah or any other visible sign of Jewish identification in public. The French community issued such warnings years ago. Belgian TV could not find a single Jew in Brussels willing to wear a kippah in public. I walked across Budapest four times (for Friday evening and Saturday daytime services), and no-one looked at...