J.K. Rowling confirmed today that there is indeed one Jewish student at Hogwarts. (Just one? Help a kid out, J.K.) Rowling wrote on Twitter that one can indeed be a chosen wizard:
.@benjaminroffman Anthony Goldstein, Ravenclaw, Jewish wizard.— J.K. Rowling (@jk_rowling) December 16, 2014
No word yet on what a Wizarding bar mitzvah looks like, but it's probably great.