Militant anticommunists sometimes tormented and massacred Jews with a sick sense of humor that would have made even the Joker blush. This included parodying or misappropriating aspects from Judaism. For example, quoting Colin Evans’s The Casebook of Forensic Detection:

To describe the events in Bucharest in 1941 as “religious matters” was stretching incredulity to the breaking point. On January 21—St. Valerian’s Day—hordes of green‐shirted members of the Iron Guard, Romania’s virulently pro‐[Reich] political party, scythed through the Jewish quarter of Bucharest, laying waste to everyone and everything. The [chaos] lasted three days and left almost six thousand dead.

An eyewitness wrote, “Perhaps the most horrifying single episode was the ‘kosher butchering’ of more than 200 Jews in the municipal slaughterhouse. The Greenshirts forced them to undress and led them to the chopping block, where they cut their throats in a horrible parody of the traditional Jewish methods of slaughtering fowl and livestock.” [The bodies were ‘then left to hang on meat hooks.’]

(Emphasis added.)

There were similar instances elsewhere.

Quoting Edward B. Westermann’s Drunk on Genocide, pages 52–3:

Verbal mockery and rituals of humiliation often incorporated a grotesque parody of Jewish religious practices. For example, some members of the Einsatzgruppen forced their victims to recite the phrase “I want to go to the Promised Land” prior to their execution. Similarly, SS camp guards at Treblinka dressed prisoners as rabbis with cowbells around their necks and forced them to supervise the latrines and respond to the question “How’s it going with the shit?”

At Treblinka, the front wall of the building housing the gas chambers was adorned with a Star of David and a curtain taken from a synagogue with the Hebrew sentence, “This is the gate through which the righteous pass.”

In some cases, the perpetrators went so far as to create ritual religious parodies as “ceremonial mockeries” of their victims’ Jewish faith. One witness in the Ukrainian town of Chudnov described the [Fascists’] use of one such “ceremonial mockery” in which the town’s eighty‐seven‐year‐old rabbi was forced to don his religious garments and was led by two women carrying candles to the execution site. Escorted by a [Fascist] with a rubber whip, “the old women were forced to sing, walking through the whole shtetl [village] until they reached the garden. […] They were killed and buried in the same pit right there in the garden, and a cross was put over their grave.”

During mass killings in Minsk, SS and police forces organized a “ceremony” on Saturdays (the Sabbath) that included Jewish musicians playing arias from the opera The Jewess and “Kol Nidre,” the opening sung prayer of the Yom Kippur service.

These acts were not only intended as a humiliation of the individual, but also to ridicule Judaism itself. By incorporating song, prayers, and religious artifacts into the killing process, the perpetrators appropriated their victims’ rituals while symbolically repudiating their Jewish faith, an act made explicit with the placing of the cross over the mass grave in Chudnov.

In addition, there was at least one instance where the Fascists intentionally selected 613 Jews to exterminate because they knew that the number 613 was sacred to Judaists. Enzo Garofalo of the Institute of Concentrationary Music Literature Foundation told me this:

[I]n derision against Jewish people, the Nazis chose 613 young guys (a number corresponding to the precepts of Judaism) and put them on a truck promising them that they would be freed. There was also a 614th young guy with them: the Nazis then said that one of them had to go down because he was supernumerary. The only one who had the intuition to get off was fourteen-year-old Jacob Garfein ([who] survived, [and] after the war [was] expatriated to the USA and became a famous theater director and well-known as Jack Garfein) who, during the trip, had heard one of the boys singing a poignant melody. Garfein recorded it in his mind without ever singing it.

(The song was Tsi itzt mayn harts by a Polish anonym from the Märzbachtal camp.)