The Halacha is that one may not serve Avodah Zarah even on pain of death (Sanhedrin 74a).
I was staying by a family for Shabbos, and their 11-year-old son asked a genius question. What happens if the threat is not “worship or I’ll kill you,” but rather “worship or I’ll kill him”? Does this Halacha still apply?
On the one hand, one could argue that what the threatener decides to do is none of your business; let him do what he wishes, and you not get involved.
On the other hand, the source that one must give up his life for Avodah Zarah, as per the above-cited Gemara, is Devarim 6:5 - “and you should love Hashem, your G-d...with all your soul.” One could argue that it’s only your soul one is obligated to give up, and you have no right to give up someone else’s soul for your love of Hashem.
What is the Halacha? I have looked in the Rambam, Tur, and Shulchan Aruch, as well as the commentaries on the above, with no success of anyone talking about anything similar to this case.