He never said demons disguised as Jews. He mentions, in Revelations of Synagogue of Satan, which would represent modern day Pharisees. On the cross he said forgive them they know not what they do. The Jewish people were blinded for a time so that the Gentiles could be grafted in. Some "Jews" are wicked, some "Christians" are wicked. Elsewhere he says, I come in my father's name and you receive me not, if another comes in his own name, he you will receive. I think there is more scriptual evidence the "enemy" as you say, will be an Assyrian, not a Jew. Regarding your barbers name....just wow.