Confusion sometimes arises between the designations, "Anti-Jewish" and "Anti-Semitism." But each term has its own history and meaning.
The term, "Anti-Jewish" developed from religious and general practices considered to be less worthy or more repugnant than those that that were associated with Christian ideals. It was based on ignorance such as the accusations that Jews were Christ-killers, indulged in blood libels* (killing Christian children in order to use their blood in preparing Passover foods), well-poisoning, or desecration of the Host (the wafer used in the Mass). It became explicit in hateful stereotypes such as prominent lips, beaked-noses. and devil-like features which appeared in posters, prints, and illustrated books. Although it could be erased by baptism and conversion, centuries of ingrained attitudes were difficult to change.
"Anti-Semitism" promoted the notion that cultural traits were revealed through lineage. By the nineteenth century, philosophic theories of rationalism became more respectable than degradation or theological systems.The "rational" scientific notion of society became based on "natural" principles." When Charles Darwin's "Origin of Species," 1859, and "Descent of Man," 1871, attributed natural selection rather than the Creator to physical and mental abilities and debilities, some racist theories suggested that an intrinsic "biological inferiority" would - and should - replace Jewish "spiritual degradation."
Since baptism or conversion could not be inherited, anti-Semitism explained that nothing could wipe clean the taint of Jewish blood. In 1881, the first avowedly anti-Jewish newspaper, "L'Anti-Juif" initiated attacks based, not on the religious component of Judaism, but on Jewish heritage alone. Ethnic "purity" suggested that race was the ultimate power that impelled or motivated society. Even as many believed those ideas were on solid scientific grounds, those arguments found their way ultimately into Nazi ideology.
Of course, to the Jews who suffered over the centuries, the distinctions between anti-Jewishness and anti-Semitism hardly mattered.
* The blood libel accusations are particularly ironic, given that Jewish dietary laws prohibit the consumption of blood. Properly koshered meat is soaked in salt water (which is discarded) in order to remove as much blood as possible. Passover matzah also has strict guidelines for its production, and the idea that it contains blood is absurd.