Let's Talk Halacha: What Are Worst Sins in Judaism?

Of the many mitzvot (commandments) of the Torah, there are very few that one is required to keep when one’s life if threatened. Almost every aspect of Jewish law can be transgressed if someone’s life is in danger (eating non-kosher, breaking the Sabbath, etc.), but among the transgressions a Jew is required to die for are the following:

Kill or Be Killed. 

Murder: If someone forces a Jew to kill someone else in order to save their own life, a Jew is basically commanded to not give that person the satisfaction. They must still refuse to kill.

Forbidden Sexual Relations. 

Rape: Because rape is frequently compared to murder in Judaism, the same rules apply: if someone were to command a Jew to sexual assault someone under pain of death if they refuse, they must still refuse.

Worship of Foreign Deities

Avodah Zara: Jews are not allowed to participate in the worship of idols: any supernatural beings besides the One G-d of Israel. This includes even the spiritual worship of even known figures, such as human figures even from the Bible or sages. This also extends to messiahs, sons of G-d, and the like. If a Jew is threatened with death if they do not worship these false gods, they are still to refuse. Because of this, Jews are also not allowed to enter any place dedicated to the worship of the gods of other faiths (churches, Hindu shrines, etc. are off limits — mosques and gurdwaras, however, are acceptable because Islam and Sikhi are considered monotheistic faiths).

The basic idea of taking upon death rather than performing these acts is to say that, yes, you can take the life of a Jew, but you cannot take our soul.