Kiddush hashem (Hebrew: קידוש השם; “sanctification of the name [of God]”) is a precept of Judaism as expressed in the Torah for any Jew: “To sanctify His Name” , and conversely not to bring dishonor or shame to God’s name which is known as Chillul Hashem: “Not to profane His Name” .
Thus any action by a Jew that brings honor, respect, and glory to God is considered to be a Kiddush Hashem, whereas any behavior or action that disgraces, harms or shames God and his Torah is regarded as a Chillul Hashem which means a “desecration of God.”
The ultimate act of Kiddush Hashem is when a Jew is prepared to sacrifice his life rather than transgress any of God’s three cardinal sins: Serving idols (belief in another religion), committing certain sexual acts (such as incest or adultery), or committing murder.
The Jews who were victims of the Spanish Inquisition who were either executed or exiled from Spain and Portugal because they did not renounce their religion and belief in God as taught by Judaism are called Kedoshim (“holy ones”) because they are regarded as having fulfilled the mitzvah (“commandment”) of Kiddush Hashem.
Another way to be categorized Kedoshim, is if someone is killed for the simple reason of being Jewish, even if not given the opportunity to convert, or otherwise disassociate with the Jewish faith. Thus, the six million Jews who were murdered during the Holocaust only because they were Jews, are considered Kedoshim.