Because for most Jews, Judaism is a tribal identity whose moral code can be boiled down to what is good for Jews. That’s how tribes work. Jews no more or less than the average in that department.
So there’s no contradiction between working as a hitman and living as an Orthodox Jew. Orthodox Jews, by and large, are the most tribal of Jews.
Tabletmag: On Yom Kippur in 1929, Louis Fleisher, Harry Fleisher, and Henry Shorr attended services at Orthodox Congregation B’nai David in Northwest Detroit. The three men—all sterling members of the Purple Gang, Detroit’s mostly Jewish mob—had plenty to atone for: The Purple Gang controlled the city’s illegal gambling, smuggled liquor during Prohibition, and had a hand in most of Detroit’s underworld vice. The gang didn’t hesitate to resort to violence—arson, bombings, and murder—when its operations were threatened. They were reputedly more ruthless than Chicago’s Capone gang.
The three gangsters didn’t notice three other men sitting in the back of the synagogue: G-men disguised in black Hasidic garb who hoped to arrest the three hoodlums after the service. But when the non-Jewish G-men lit up cigarettes during the intermission, not knowing that striking a match or lighting a fire is forbidden on Yom Kippur, their cover was blown and the gangsters got away.
The men of the Purple Gang weren’t the only Jewish mobsters who observed Jewish rituals, even as they committed crimes that broke all of the Ten Commandments, as I discovered while doing research for my book on Jewish mobsters, But He Was Good to His Mother: The Lives and Crimes of Jewish Gangsters. When examining FBI files and interviewing old-time Jewish criminals and their relatives, I found that plenty of Jewish mobsters prayed in synagogue on Shabbat, observed Jewish holidays, maintained religious rituals, fasted on Yom Kippur, and attended Passover Seders.
Sam “Red” Levine provides a singular illustration of this. Levine was New York City gangster Charley “Lucky” Luciano’s favorite contract killer. According to Martin Gosch and Richard Hammer’s 1975 book The Last Testament of Lucky Luciano, Lucky called Red “the best driver and hitman I had.” Red also had another persona: He was an Orthodox Jew. He always wore a kipah under his hat, ate only kosher food, and conscientiously observed the Sabbath. Levine never planned to murder anyone from Friday sundown to Saturday sundown. But, according to Gosch and Hammer, if Levine had no choice and had to make the hit on Shabbat, he would first put on a tallit, say his prayers, and then go and do the job.