I've never heard anyone make the connection between crucifixion and circumcision before. It is an odd connection to make because not only do you have to make the false connection between crucifiction and the Jews (as you point out) but also you have to associate it with one of countless rituals observed in Judaism. It is far-fetched enough without including a 16th century painting that most Europeans have never even seen... Oh and the crucifix is not a "classroom standard" in Europe, you are referring to a verdict that rejected the ban of a crucifix in an Italian school. There is quite a difference between that and your description. By and large Europe is very unreligious, compared to say the US or Israel. Quite frankly you seem rather ignorant of the (non-) importance of religion in Europe.
Key U.S. House Democrat cites troublesome issues in Iran nuclear deal (Reuters)
from the article: Europe's shudder at circumcision