Jews have been living defensively for a long time. But when a synagogue, as a precaution, decides not to post the time of services, we have reached a new level. In Spain in the 15th century, many Jews sought safety from persecution by converting to Christianity but secretly maintained their Jewish practices. They lit Shabbat candles in inner reaches of their homes where no one from the street could see, and eschewed eating pork or shellfish. They became what Spaniards called Marranos, a term of degradation comparable in some ways to kike. Some Jews who converted did not maintain the traditions. This did not, of course, guarantee their safety when the Church, state authorities, and the mob began to seek out Marranos for persecution.

I use the term, however reluctantly, because it captures what I am seeing today. Most Jewish students on American campuses have not been subjected to overt acts of discrimination or verbal abuse. But many among them feel they have something to lose if they openly identify as Jews. If they are active in Hillel, the Jewish student organization, they may be informally barred from being active in progressive causes—for example, racial and LGBTQ equality, climate-change mitigation, and the fight against sexual assault. Those who want to be elected to student government are learning to scrub their résumés clean of any overtly Jewish or pro-Israel activities. They are not abandoning their Jewish identity; they are hiding it. They have become Marranos.

When Jews feel it is safer for them to go “underground” as Jews, something is terribly wrong—wrong for them and, even more so, wrong for the society in which they live. Jews have taken and are taking anti-Semitism very seriously. Non-Jews must do the same.