In “This column is anti-Orthodox” (Oct. 29), Rabbi Shammai Engelmayer contends that “‘The Orthodox’ does not exist” since there are so many diverse types of Jews claiming that label. He correctly points out the vast differences between Orthodox Rabbis Avi Weiss and Avi Shafran, Moshe Feinstein and J.B. Soloveitchik, as well as Satmar and Chabad chasidim, etc. Yes, there are many differences among Jews who describe themselves as Orthodox – how they dress, how much Torah they learn, how often they attend synagogue, whether they own a TV, access the Internet, and dozens more. But the point that Rabbi Englemayer seems to miss is that what makes them all Orthodox is what they share with each other and with any Jew who claims that designation. And that is a core set of immutable observances.

In “Fiddler on the Roof,” Tevye, after tolerating the deviation from tradition by his two oldest daughters, has to decide whether to accept the planned intermarriage of another daughter. His decision: “If I bend that far I’ll break. No! No! No!” So too, except in the case of extreme danger to one’s health, virtually each and every Jew who considers himself or herself to be Orthodox would recoil with revulsion and exclaim “No! No! No!” at the mere thought of performing any of the acts listed below. Please note that this list is not found in any book on Jewish law. Instead, it is based on my personal observations of the everyday practices of hundreds of Orthodox Jews over dozens of years. I admit that there are some acts I might have missed but no Jew who describes himself or herself as Orthodox would ever:

• Intermarry

• Drive on Shabbat

• Shop on Shabbat

• Watch TV or use a phone, computer, or any electrical device on Shabbat

• Choose to not circumcise a son

• Eat pig

• Eat shellfish

• Eat dairy and meat together

• Eat dairy without waiting at least one hour after eating meat

• Eat meat lacking kosher certification

• Eat or drink on Yom Kippur

• Eat chametz on Passover

While there are Conservative Jews and perhaps Reform Jews who do not perform any of these acts, there are surely many who perform at least some of them. Therefore, such a core set of observances can serve as the litmus test to answer the question “Who is an Orthodox Jew?”