I recall some years ago visiting a hotel, and encountering a young man wearing a yarmulke. We met in the lobby of the hotel. After we got on the elevator, he asked me for a favor. He asked me if I would unlock the door of his hotel room for him. You see, the hotel has electronic locks, and operating the hotel's lock was, in the view of this Jewish man, a violation of the Sabbath.
Oddly, he had not the least compunction in asking me to violate the Sabbath for him. I disagreed with the man's theonomy, and so I agreed to assist. I pressed the elevator button for him, and I unlocked his door for him. I thought it would be pointless to dispute the matter with him.
Later I investigated whether this was normal or not. After all, normally if something is wrong, it is wrong to ask someone else to do that wrong thing for you. One cannot ask a stranger on a train to murder one's father, nor (thought I) could one ask a stranger in a hotel lobby to violate the Sabbath. It turns out that the standard Jewish response to the latter question is to distinguish.
Apparently, the standard Jewish answer is that the Sabbath is only for the Jews, not for the Gentiles. Thus, it's perfectly ok for me (who the young man assumed to be a Gentile) to break the Sabbath, but not ok for me to kill (since prohibitions on murder are more universal).
Why do I bring this up now? The reason I bring it up is because I had a tasty dinner of Rotini with Meat Sauce on a Friday during Lent. I'm interested in Catholic opinion on the matter. Do Catholics think that Lent applies to Christians that are not Catholics? What about to formal/material heretics? In other words, is Lent to Catholics as the Sabbath is to Jews?
On the other side of the spectrum, I am aware that Ramadan in some Muslim countries is enforced by the police. It is not a defense to a charge of breaking Ramadan in any public place that you are not a Muslim.
Furthermore, such a view is not entirely outside Catholicism. Recall that the Fourth Lateran Council decreed:
68. Jews appearing in public
A difference of dress distinguishes Jews or Saracens from Christians in some provinces, but in others a certain confusion has developed so that they are indistinguishable. Whence it sometimes happens that by mistake Christians join with Jewish or Saracen women, and Jews or Saracens with christian women. In order that the offence of such a damnable mixing may not spread further, under the excuse of a mistake of this kind, we decree that such persons of either sex, in every christian province and at all times, are to be distinguished in public from other people by the character of their dress -- seeing moreover that this was enjoined upon them by Moses himself, as we read. They shall not appear in public at all on the days of lamentation and on passion Sunday; because some of them on such days, as we have heard, do not blush to parade in very ornate dress and are not afraid to mock Christians who are presenting a memorial of the most sacred passion and are displaying signs of grief. What we most strictly forbid however, is that they dare in any way to break out in derision of the Redeemer. We order secular princes to restrain with condign punishment those who do so presume, lest they dare to blaspheme in any way him who was crucified for us, since we ought not to ignore insults against him who blotted out our wrongdoings.
So then, the simple question is: is my consumption of Rotini with meat sauce on Friday during Lent a mortal sin for me, or only for my Catholic neighbors? Is Lent more like Ramadan or the Jewish Sabbath? And if the latter, would you please pass the meatballs?
UPDATE: I realize that Orthodox views on Lenten fasting are somewhat diferent. I'd be interested in Orthodox thoughts on whether it is sin for Reformed Christians to violate the various prohibitions on eating, drinking, and sex during that period.
Further Update: Thanks to Reginald for his well-reasoned response from a Catholic perspective here (link). If I may summarize his answer: in his view it is more like the Jewish Sabbath, in that it is permitted for non-Catholics to ignore the fast, because the moral basis of obligation is dependent on the duty of Catholics to obey their church.